VI(1P) POSIX Programmer's Manual VI(1P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEvi — screen-oriented (visual) display editor
SYNOPSISvi [−rR] [−c command] [−t tagstring] [−w size] [file...]
DESCRIPTION
This utility shall be provided on systems that both support the User
Portability Utilities option and define the POSIX2_CHAR_TERM symbol.
On other systems it is optional.
The vi (visual) utility is a screen-oriented text editor. Only the open
and visual modes of the editor are described in POSIX.1‐2008; see the
line editor ex for additional editing capabilities used in vi. The
user can switch back and forth between vi and ex and execute ex com‐
mands from within vi.
This reference page uses the term edit buffer to describe the current
working text. No specific implementation is implied by this term. All
editing changes are performed on the edit buffer, and no changes to it
shall affect any file until an editor command writes the file.
When using vi, the terminal screen acts as a window into the editing
buffer. Changes made to the editing buffer shall be reflected in the
screen display; the position of the cursor on the screen shall indicate
the position within the editing buffer.
Certain terminals do not have all the capabilities necessary to support
the complete vi definition. When these commands cannot be supported on
such terminals, this condition shall not produce an error message such
as ``not an editor command'' or report a syntax error. The implementa‐
tion may either accept the commands and produce results on the screen
that are the result of an unsuccessful attempt to meet the requirements
of this volume of POSIX.1‐2008 or report an error describing the termi‐
nal-related deficiency.
OPTIONS
The vi utility shall conform to the Base Definitions volume of
POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines, except that '+'
may be recognized as an option delimiter as well as '−'.
The following options shall be supported:
−c command
See the ex command description of the −c option.
−r See the ex command description of the −r option.
−R See the ex command description of the −R option.
−t tagstring
See the ex command description of the −t option.
−w size See the ex command description of the −w option.
OPERANDS
See the OPERANDS section of the ex command for a description of the op‐
erands supported by the vi command.
STDIN
If standard input is not a terminal device, the results are undefined.
The standard input consists of a series of commands and input text, as
described in the EXTENDED DESCRIPTION section.
If a read from the standard input returns an error, or if the editor
detects an end-of-file condition from the standard input, it shall be
equivalent to a SIGHUP asynchronous event.
INPUT FILES
See the INPUT FILES section of the ex command for a description of the
input files supported by the vi command.
ENVIRONMENT VARIABLES
See the ENVIRONMENT VARIABLES section of the ex command for the envi‐
ronment variables that affect the execution of the vi command.
ASYNCHRONOUS EVENTS
See the ASYNCHRONOUS EVENTS section of the ex for the asynchronous
events that affect the execution of the vi command.
STDOUT
If standard output is not a terminal device, undefined results occur.
Standard output may be used for writing prompts to the user, for infor‐
mational messages, and for writing lines from the file.
STDERR
If standard output is not a terminal device, undefined results occur.
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
See the OUTPUT FILES section of the ex command for a description of the
output files supported by the vi command.
EXTENDED DESCRIPTION
If the terminal does not have the capabilities necessary to support an
unspecified portion of the vi definition, implementations shall start
initially in ex mode or open mode. Otherwise, after initialization, vi
shall be in command mode; text input mode can be entered by one of sev‐
eral commands used to insert or change text. In text input mode, <ESC>
can be used to return to command mode; other uses of <ESC> are
described later in this section; see Terminate Command or Input Mode.
Initialization in ex and vi
See Initialization in ex and vi for a description of ex and vi initial‐
ization for the vi utility.
Command Descriptions in vi
The following symbols are used in this reference page to represent
arguments to commands.
buffer See the description of buffer in the EXTENDED DESCRIPTION sec‐
tion of the ex utility; see Command Descriptions in ex.
In open and visual mode, when a command synopsis shows both
[buffer] and [count] preceding the command name, they can be
specified in either order.
count A positive integer used as an optional argument to most com‐
mands, either to give a repeat count or as a size. This argu‐
ment is optional and shall default to 1 unless otherwise speci‐
fied.
The Synopsis lines for the vi commands <control>‐G, <con‐
trol>‐L, <control>‐R, <control>‐], %, &, ^, D, m, M, Q, u, U,
and ZZ do not have count as an optional argument. Regardless,
it shall not be an error to specify a count to these commands,
and any specified count shall be ignored.
motion An optional trailing argument used by the !, <, >, c, d, and y
commands, which is used to indicate the region of text that
shall be affected by the command. The motion can be either one
of the command characters repeated or one of several other vi
commands (listed in the following table). Each of the applica‐
ble commands specifies the region of text matched by repeating
the command; each command that can be used as a motion command
specifies the region of text it affects.
Commands that take motion arguments operate on either lines or
characters, depending on the circumstances. When operating on
lines, all lines that fall partially or wholly within the text
region specified for the command shall be affected. When oper‐
ating on characters, only the exact characters in the specified
text region shall be affected. Each motion command specifies
this individually.
When commands that may be motion commands are not used as
motion commands, they shall set the current position to the
current line and column as specified.
The following commands shall be valid cursor motion commands:
<apostrophe> ( - j H
<carriage-return> ) $ k L
<comma> [[ % l M
<control>-H ]] _ n N
<control>-N { ; t T
<control>-P } ? w W
<grave-accent> ^ b B
<newline> + e E
<space> | f F
<zero> / h G
Any count that is specified to a command that has an associated
motion command shall be applied to the motion command. If a
count is applied to both the command and its associated motion
command, the effect shall be multiplicative.
The following symbols are used in this section to specify locations in
the edit buffer:
current character
The character that is currently indicated by the cursor.
end of a line
The point located between the last non-<newline> (if any) and
the terminating <newline> of a line. For an empty line, this
location coincides with the beginning of the line.
end of the edit buffer
The location corresponding to the end of the last line in the
edit buffer.
The following symbols are used in this section to specify command
actions:
bigword In the POSIX locale, vi shall recognize four kinds of bigwords:
1. A maximal sequence of non-<blank> characters preceded and
followed by <blank> characters or the beginning or end of a
line or the edit buffer
2. One or more sequential blank lines
3. The first character in the edit buffer
4. The last non-<newline> in the edit buffer
word In the POSIX locale, vi shall recognize five kinds of words:
1. A maximal sequence of letters, digits, and underscores,
delimited at both ends by:
-- Characters other than letters, digits, or underscores
-- The beginning or end of a line
-- The beginning or end of the edit buffer
2. A maximal sequence of characters other than letters, dig‐
its, underscores, or <blank> characters, delimited at both
ends by:
-- A letter, digit, underscore
-- <blank> characters
-- The beginning or end of a line
-- The beginning or end of the edit buffer
3. One or more sequential blank lines
4. The first character in the edit buffer
5. The last non-<newline> in the edit buffer
section boundary
A section boundary is one of the following:
1. A line whose first character is a <form-feed>
2. A line whose first character is an open curly brace ('{')
3. A line whose first character is a <period> and whose second
and third characters match a two-character pair in the sec‐
tions edit option (see ed)
4. A line whose first character is a <period> and whose only
other character matches the first character of a two-char‐
acter pair in the sections edit option, where the second
character of the two-character pair is a <space>
5. The first line of the edit buffer
6. The last line of the edit buffer if the last line of the
edit buffer is empty or if it is a ]] or } command; other‐
wise, the last non-<newline> of the last line of the edit
buffer
paragraph boundary
A paragraph boundary is one of the following:
1. A section boundary
2. A line whose first character is a <period> and whose second
and third characters match a two-character pair in the
paragraphs edit option (see ed)
3. A line whose first character is a <period> and whose only
other character matches the first character of a two-char‐
acter pair in the paragraphs edit option, where the second
character of the two-character pair is a <space>
4. One or more sequential blank lines
remembered search direction
See the description of remembered search direction in ed.
sentence boundary
A sentence boundary is one of the following:
1. A paragraph boundary
2. The first non-<blank> that occurs after a paragraph bound‐
ary
3. The first non-<blank> that occurs after a <period> ('.'),
<exclamation-mark> ('!'), or <question-mark> ('?'), fol‐
lowed by two <space> characters or the end of a line; any
number of closing parenthesis (')'), closing brackets
(']'), double-quote ('"'), or single-quote (<apostrophe>)
characters can appear between the punctuation mark and the
two <space> characters or end-of-line
In the remainder of the description of the vi utility, the term ``buf‐
fer line'' refers to a line in the edit buffer and the term ``display
line'' refers to the line or lines on the display screen used to dis‐
play one buffer line. The term ``current line'' refers to a specific
``buffer line''.
If there are display lines on the screen for which there are no corre‐
sponding buffer lines because they correspond to lines that would be
after the end of the file, they shall be displayed as a single <tilde>
('~') character, plus the terminating <newline>.
The last line of the screen shall be used to report errors or display
informational messages. It shall also be used to display the input for
``line-oriented commands'' (/, ?, :, and !). When a line-oriented com‐
mand is executed, the editor shall enter text input mode on the last
line on the screen, using the respective command characters as prompt
characters. (In the case of the ! command, the associated motion shall
be entered by the user before the editor enters text input mode.) The
line entered by the user shall be terminated by a <newline>, a
non-<control>‐V-escaped <carriage-return>, or unescaped <ESC>. It is
unspecified if more characters than require a display width minus one
column number of screen columns can be entered.
If any command is executed that overwrites a portion of the screen
other than the last line of the screen (for example, the ex suspend or
! commands), other than the ex shell command, the user shall be
prompted for a character before the screen is refreshed and the edit
session continued.
<tab> characters shall take up the number of columns on the screen set
by the tabstop edit option (see ed), unless there are less than that
number of columns before the display margin that will cause the dis‐
played line to be folded; in this case, they shall only take up the
number of columns up to that boundary.
The cursor shall be placed on the current line and relative to the cur‐
rent column as specified by each command described in the following
sections.
In open mode, if the current line is not already displayed, then it
shall be displayed.
In visual mode, if the current line is not displayed, then the lines
that are displayed shall be expanded, scrolled, or redrawn to cause an
unspecified portion of the current line to be displayed. If the screen
is redrawn, no more than the number of display lines specified by the
value of the window edit option shall be displayed (unless the current
line cannot be completely displayed in the number of display lines
specified by the window edit option) and the current line shall be
positioned as close to the center of the displayed lines as possible
(within the constraints imposed by the distance of the line from the
beginning or end of the edit buffer). If the current line is before the
first line in the display and the screen is scrolled, an unspecified
portion of the current line shall be placed on the first line of the
display. If the current line is after the last line in the display and
the screen is scrolled, an unspecified portion of the current line
shall be placed on the last line of the display.
In visual mode, if a line from the edit buffer (other than the current
line) does not entirely fit into the lines at the bottom of the display
that are available for its presentation, the editor may choose not to
display any portion of the line. The lines of the display that do not
contain text from the edit buffer for this reason shall each consist of
a single '@' character.
In visual mode, the editor may choose for unspecified reasons to not
update lines in the display to correspond to the underlying edit buffer
text. The lines of the display that do not correctly correspond to text
from the edit buffer for this reason shall consist of a single '@'
character (plus the terminating <newline>), and the <control>‐R command
shall cause the editor to update the screen to correctly represent the
edit buffer.
Open and visual mode commands that set the current column set it to a
column position in the display, and not a character position in the
line. In this case, however, the column position in the display shall
be calculated for an infinite width display; for example, the column
related to a character that is part of a line that has been folded onto
additional screen lines will be offset from the display line column
where the buffer line begins, not from the beginning of a particular
display line.
The display cursor column in the display is based on the value of the
current column, as follows, with each rule applied in turn:
1. If the current column is after the last display line column used by
the displayed line, the display cursor column shall be set to the
last display line column occupied by the last non-<newline> in the
current line; otherwise, the display cursor column shall be set to
the current column.
2. If the character of which some portion is displayed in the display
line column specified by the display cursor column requires more
than a single display line column:
a. If in text input mode, the display cursor column shall be
adjusted to the first display line column in which any portion
of that character is displayed.
b. Otherwise, the display cursor column shall be adjusted to the
last display line column in which any portion of that character
is displayed.
The current column shall not be changed by these adjustments to the
display cursor column.
If an error occurs during the parsing or execution of a vi command:
* The terminal shall be alerted. Execution of the vi command shall
stop, and the cursor (for example, the current line and column)
shall not be further modified.
* Unless otherwise specified by the following command sections, it is
unspecified whether an informational message shall be displayed.
* Any partially entered vi command shall be discarded.
* If the vi command resulted from a map expansion, all characters
from that map expansion shall be discarded, except as otherwise
specified by the map command (see ed).
* If the vi command resulted from the execution of a buffer, no fur‐
ther commands caused by the execution of the buffer shall be exe‐
cuted.
Page Backwards
Synopsis:
[count] <control>-B
If in open mode, the <control>‐B command shall behave identically to
the z command. Otherwise, if the current line is the first line of the
edit buffer, it shall be an error.
If the window edit option is less than 3, display a screen where the
last line of the display shall be some portion of:
(current first line) −1
otherwise, display a screen where the first line of the display shall
be some portion of:
(current first line) − count x ((window edit option) −2)
If this calculation would result in a line that is before the first
line of the edit buffer, the first line of the display shall display
some portion of the first line of the edit buffer.
Current line: If no lines from the previous display remain on the
screen, set to the last line of the display; otherwise, set to (line −
the number of new lines displayed on this screen).
Current column: Set to non-<blank>.
Scroll Forward
Synopsis:
[count] <control>-D
If the current line is the last line of the edit buffer, it shall be an
error.
If no count is specified, count shall default to the count associated
with the previous <control>‐D or <control>‐U command. If there was no
previous <control>‐D or <control>‐U command, count shall default to the
value of the scroll edit option.
If in open mode, write lines starting with the line after the current
line, until count lines or the last line of the file have been written.
Current line: If the current line + count is past the last line of the
edit buffer, set to the last line of the edit buffer; otherwise, set to
the current line + count.
Current column: Set to non-<blank>.
Scroll Forward by Line
Synopsis:
[count] <control>-E
Display the line count lines after the last line currently displayed.
If the last line of the edit buffer is displayed, it shall be an error.
If there is no line count lines after the last line currently dis‐
played, the last line of the display shall display some portion of the
last line of the edit buffer.
Current line: Unchanged if the previous current character is displayed;
otherwise, set to the first line displayed.
Current column: Unchanged.
Page Forward
Synopsis:
[count] <control>-F
If in open mode, the <control>‐F command shall behave identically to
the z command. Otherwise, if the current line is the last line of the
edit buffer, it shall be an error.
If the window edit option is less than 3, display a screen where the
first line of the display shall be some portion of:
(current last line) +1
otherwise, display a screen where the first line of the display shall
be some portion of:
(current first line) + count x ((window edit option) −2)
If this calculation would result in a line that is after the last line
of the edit buffer, the last line of the display shall display some
portion of the last line of the edit buffer.
Current line: If no lines from the previous display remain on the
screen, set to the first line of the display; otherwise, set to (line +
the number of new lines displayed on this screen).
Current column: Set to non-<blank>.
Display Information
Synopsis:
<control>-G
This command shall be equivalent to the ex file command.
Move Cursor Backwards
Synopsis:
[count] <control>-H
[count] h
the current erase character (see stty)
If there are no characters before the current character on the current
line, it shall be an error. If there are less than count previous char‐
acters on the current line, count shall be adjusted to the number of
previous characters on the line.
If used as a motion command:
1. The text region shall be from the character before the starting
cursor up to and including the countth character before the start‐
ing cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to (column − the number of columns occupied by
count characters ending with the previous current column).
Move Down
Synopsis:
[count] <newline>
[count] <control>-J
[count] <control>-M
[count] <control>-N
[count] j
[count] <carriage-return>
[count] +
If there are less than count lines after the current line in the edit
buffer, it shall be an error.
If used as a motion command:
1. The text region shall include the starting line and the next count
− 1 lines.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line+ count.
Current column: Set to non-<blank> for the <carriage-return>, <con‐
trol>‐M, and + commands; otherwise, unchanged.
Clear and Redisplay
Synopsis:
<control>-L
If in open mode, clear the screen and redisplay the current line. Oth‐
erwise, clear and redisplay the screen.
Current line: Unchanged.
Current column: Unchanged.
Move Up
Synopsis:
[count] <control>-P
[count] k
[count] −
If there are less than count lines before the current line in the edit
buffer, it shall be an error.
If used as a motion command:
1. The text region shall include the starting line and the previous
count lines.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line − count.
Current column: Set to non-<blank> for the − command; otherwise,
unchanged.
Redraw Screen
Synopsis:
<control>-R
If any lines have been deleted from the display screen and flagged as
deleted on the terminal using the @ convention (see the beginning of
the EXTENDED DESCRIPTION section), they shall be redisplayed to match
the contents of the edit buffer.
It is unspecified whether lines flagged with @ because they do not fit
on the terminal display shall be affected.
Current line: Unchanged.
Current column: Unchanged.
Scroll Backward
Synopsis:
[count] <control>-U
If the current line is the first line of the edit buffer, it shall be
an error.
If no count is specified, count shall default to the count associated
with the previous <control>‐D or <control>‐U command. If there was no
previous <control>‐D or <control>‐U command, count shall default to the
value of the scroll edit option.
Current line: If count is greater than the current line, set to 1; oth‐
erwise, set to the current line − count.
Current column: Set to non-<blank>.
Scroll Backward by Line
Synopsis:
[count] <control>-Y
Display the line count lines before the first line currently displayed.
If the current line is the first line of the edit buffer, it shall be
an error. If this calculation would result in a line that is before the
first line of the edit buffer, the first line of the display shall dis‐
play some portion of the first line of the edit buffer.
Current line: Unchanged if the previous current character is displayed;
otherwise, set to the first line displayed.
Current column: Unchanged.
Edit the Alternate File
Synopsis:
<control>-^
This command shall be equivalent to the ex edit command, with the
alternate pathname as its argument.
Terminate Command or Input Mode
Synopsis:
<ESC>
If a partial vi command (as defined by at least one, non-count charac‐
ter) has been entered, discard the count and the command character(s).
Otherwise, if no command characters have been entered, and the <ESC>
was the result of a map expansion, the terminal shall be alerted and
the <ESC> character shall be discarded, but it shall not be an error.
Otherwise, it shall be an error.
Current line: Unchanged.
Current column: Unchanged.
Search for tagstring
Synopsis:
<control>-]
If the current character is not a word or <blank>, it shall be an
error.
This command shall be equivalent to the ex tag command, with the argu‐
ment to that command defined as follows.
If the current character is a <blank>:
1. Skip all <blank> characters after the cursor up to the end of the
line.
2. If the end of the line is reached, it shall be an error.
Then, the argument to the ex tag command shall be the current character
and all subsequent characters, up to the first non-word character or
the end of the line.
Move Cursor Forward
Synopsis:
[count] <space>
[count] l (ell)
If there are less than count non-<newline> characters after the cursor
on the current line, count shall be adjusted to the number of non-<new‐
line> characters after the cursor on the line.
If used as a motion command:
1. If the current or countth character after the cursor is the last
non-<newline> in the line, the text region shall be comprised of
the current character up to and including the last non-<newline> in
the line. Otherwise, the text region shall be from the current
character up to, but not including, the countth character after the
cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
If there are no non-<newline> characters after the current character on
the current line, it shall be an error.
Current line: Unchanged.
Current column: Set to the last column that displays any portion of the
countth character after the current character.
Replace Text with Results from Shell Command
Synopsis:
[count] ! motion shell-commands <newline>
If the motion command is the ! command repeated:
1. If the edit buffer is empty and no count was supplied, the command
shall be the equivalent of the ex :read ! command, with the text
input, and no text shall be copied to any buffer.
2. Otherwise:
a. If there are less than count −1 lines after the current line in
the edit buffer, it shall be an error.
b. The text region shall be from the current line up to and
including the next count −1 lines.
Otherwise, the text region shall be the lines in which any character of
the text region specified by the motion command appear.
Any text copied to a buffer shall be in line mode.
This command shall be equivalent to the ex ! command for the specified
lines.
Move Cursor to End-of-Line
Synopsis:
[count] $
It shall be an error if there are less than (count −1) lines after the
current line in the edit buffer.
If used as a motion command:
1. If count is 1:
a. It shall be an error if the line is empty.
b. Otherwise, the text region shall consist of all characters from
the starting cursor to the last non-<newline> in the line,
inclusive, and any text copied to a buffer shall be in charac‐
ter mode.
2. Otherwise, if the starting cursor position is at or before the
first non-<blank> in the line, the text region shall consist of the
current and the next count −1 lines, and any text saved to a buffer
shall be in line mode.
3. Otherwise, the text region shall consist of all characters from the
starting cursor to the last non-<newline> in the line that is count
−1 lines forward from the current line, and any text copied to a
buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the current line + count−1.
Current column: The current column is set to the last display line col‐
umn of the last non-<newline> in the line, or column position 1 if the
line is empty.
The current column shall be adjusted to be on the last display line
column of the last non-<newline> of the current line as subsequent com‐
mands change the current line, until a command changes the current col‐
umn.
Move to Matching Character
Synopsis:
%
If the character at the current position is not a parenthesis, bracket,
or curly brace, search forward in the line to the first one of those
characters. If no such character is found, it shall be an error.
The matching character shall be the parenthesis, bracket, or curly
brace matching the parenthesis, bracket, or curly brace, respectively,
that was at the current position or that was found on the current line.
Matching shall be determined as follows, for an open parenthesis:
1. Set a counter to 1.
2. Search forwards until a parenthesis is found or the end of the edit
buffer is reached.
3. If the end of the edit buffer is reached, it shall be an error.
4. If an open parenthesis is found, increment the counter by 1.
5. If a close parenthesis is found, decrement the counter by 1.
6. If the counter is zero, the current character is the matching char‐
acter.
Matching for a close parenthesis shall be equivalent, except that the
search shall be backwards, from the starting character to the beginning
of the buffer, a close parenthesis shall increment the counter by 1,
and an open parenthesis shall decrement the counter by 1.
Matching for brackets and curly braces shall be equivalent, except that
searching shall be done for open and close brackets or open and close
curly braces. It is implementation-defined whether other characters are
searched for and matched as well.
If used as a motion command:
1. If the matching cursor was after the starting cursor in the edit
buffer, and the starting cursor position was at or before the first
non-<blank> non-<newline> in the starting line, and the matching
cursor position was at or after the last non-<blank> non-<newline>
in the matching line, the text region shall consist of the current
line to the matching line, inclusive, and any text copied to a buf‐
fer shall be in line mode.
2. If the matching cursor was before the starting cursor in the edit
buffer, and the starting cursor position was at or after the last
non-<blank> non-<newline> in the starting line, and the matching
cursor position was at or before the first non-<blank> non-<new‐
line> in the matching line, the text region shall consist of the
current line to the matching line, inclusive, and any text copied
to a buffer shall be in line mode.
3. Otherwise, the text region shall consist of the starting character
to the matching character, inclusive, and any text copied to a buf‐
fer shall be in character mode.
If not used as a motion command:
Current line: Set to the line where the matching character is located.
Current column: Set to the last column where any portion of the match‐
ing character is displayed.
Repeat Substitution
Synopsis:
&
Repeat the previous substitution command. This command shall be equiva‐
lent to the ex & command with the current line as its addresses, and
without options, count, or flags.
Return to Previous Context at Beginning of Line
Synopsis:
' character
It shall be an error if there is no line in the edit buffer marked by
character.
If used as a motion command:
1. If the starting cursor is after the marked cursor, then the loca‐
tions of the starting cursor and the marked cursor in the edit buf‐
fer shall be logically swapped.
2. The text region shall consist of the starting line up to and
including the marked line, and any text copied to a buffer shall be
in line mode.
If not used as a motion command:
Current line: Set to the line referenced by the mark.
Current column: Set to non-<blank>.
Return to Previous Context
Synopsis:
` character
It shall be an error if the marked line is no longer in the edit buf‐
fer. If the marked line no longer contains a character in the saved
numbered character position, it shall be as if the marked position is
the first non-<blank>.
If used as a motion command:
1. It shall be an error if the marked cursor references the same char‐
acter in the edit buffer as the starting cursor.
2. If the starting cursor is after the marked cursor, then the loca‐
tions of the starting cursor and the marked cursor in the edit buf‐
fer shall be logically swapped.
3. If the starting line is empty or the starting cursor is at or
before the first non-<blank> non-<newline> of the starting line,
and the marked cursor line is empty or the marked cursor references
the first character of the marked cursor line, the text region
shall consist of all lines containing characters from the starting
cursor to the line before the marked cursor line, inclusive, and
any text copied to a buffer shall be in line mode.
4. Otherwise, if the marked cursor line is empty or the marked cursor
references a character at or before the first non-<blank> non-<new‐
line> of the marked cursor line, the region of text shall be from
the starting cursor to the last non-<newline> of the line before
the marked cursor line, inclusive, and any text copied to a buffer
shall be in character mode.
5. Otherwise, the region of text shall be from the starting cursor
(inclusive), to the marked cursor (exclusive), and any text copied
to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line referenced by the mark.
Current column: Set to the last column in which any portion of the
character referenced by the mark is displayed.
Return to Previous Section
Synopsis:
[count] [[
Move the cursor backward through the edit buffer to the first character
of the previous section boundary, count times.
If used as a motion command:
1. If the starting cursor was at the first character of the starting
line or the starting line was empty, and the first character of the
boundary was the first character of the boundary line, the text
region shall consist of the current line up to and including the
line where the countth next boundary starts, and any text copied to
a buffer shall be in line mode.
2. If the boundary was the last line of the edit buffer or the last
non-<newline> of the last line of the edit buffer, the text region
shall consist of the last character in the edit buffer up to and
including the starting character, and any text saved to a buffer
shall be in character mode.
3. Otherwise, the text region shall consist of the starting character
up to but not including the first character in the countth next
boundary, and any text copied to a buffer shall be in character
mode.
If not used as a motion command:
Current line: Set to the line where the countth next boundary in the
edit buffer starts.
Current column: Set to the last column in which any portion of the
first character of the countth next boundary is displayed, or column
position 1 if the line is empty.
Move to Next Section
Synopsis:
[count] ]]
Move the cursor forward through the edit buffer to the first character
of the next section boundary, count times.
If used as a motion command:
1. If the starting cursor was at the first character of the starting
line or the starting line was empty, and the first character of the
boundary was the first character of the boundary line, the text
region shall consist of the current line up to and including the
line where the countth previous boundary starts, and any text
copied to a buffer shall be in line mode.
2. If the boundary was the first line of the edit buffer, the text
region shall consist of the first character in the edit buffer up
to but not including the starting character, and any text copied to
a buffer shall be in character mode.
3. Otherwise, the text region shall consist of the first character in
the countth previous section boundary up to but not including the
starting character, and any text copied to a buffer shall be in
character mode.
If not used as a motion command:
Current line: Set to the line where the countth previous boundary in
the edit buffer starts.
Current column: Set to the last column in which any portion of the
first character of the countth previous boundary is displayed, or col‐
umn position 1 if the line is empty.
Move to First Non-<blank> Position on Current Line
Synopsis:
^
If used as a motion command:
1. If the line has no non-<blank> non-<newline> characters, or if the
cursor is at the first non-<blank> non-<newline> of the line, it
shall be an error.
2. If the cursor is before the first non-<blank> non-<newline> of the
line, the text region shall be comprised of the current character,
up to, but not including, the first non-<blank> non-<newline> of
the line.
3. If the cursor is after the first non-<blank> non-<newline> of the
line, the text region shall be from the character before the start‐
ing cursor up to and including the first non-<blank> non-<newline>
of the line.
4. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to non-<blank>.
Current and Line Above
Synopsis:
[count] _
If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
If used as a motion command:
1. If count is less than 2, the text region shall be the current line.
2. Otherwise, the text region shall include the starting line and the
next count −1 lines.
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to current line + count −1.
Current column: Set to non-<blank>.
Move Back to Beginning of Sentence
Synopsis:
[count] (
Move backward to the beginning of a sentence. This command shall be
equivalent to the [[ command, with the exception that sentence bound‐
aries shall be used instead of section boundaries.
Move Forward to Beginning of Sentence
Synopsis:
[count] )
Move forward to the beginning of a sentence. This command shall be
equivalent to the ]] command, with the exception that sentence bound‐
aries shall be used instead of section boundaries.
Move Back to Preceding Paragraph
Synopsis:
[count] {
Move back to the beginning of the preceding paragraph. This command
shall be equivalent to the [[ command, with the exception that para‐
graph boundaries shall be used instead of section boundaries.
Move Forward to Next Paragraph
Synopsis:
[count] }
Move forward to the beginning of the next paragraph. This command shall
be equivalent to the ]] command, with the exception that paragraph
boundaries shall be used instead of section boundaries.
Move to Specific Column Position
Synopsis:
[count] |
For the purposes of this command, lines that are too long for the cur‐
rent display and that have been folded shall be treated as having a
single, 1−based, number of columns.
If there are less than count columns in which characters from the cur‐
rent line are displayed on the screen, count shall be adjusted to be
the last column in which any portion of the line is displayed on the
screen.
If used as a motion command:
1. If the line is empty, or the cursor character is the same as the
character on the countth column of the line, it shall be an error.
2. If the cursor is before the countth column of the line, the text
region shall be comprised of the current character, up to but not
including the character on the countth column of the line.
3. If the cursor is after the countth column of the line, the text
region shall be from the character before the starting cursor up to
and including the character on the countth column of the line.
4. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
character that is displayed in the count column of the line is dis‐
played.
Reverse Find Character
Synopsis:
[count] ,
If the last F, f, T, or t command was F, f, T, or t, this command shall
be equivalent to an f, F, t, or T command, respectively, with the spec‐
ified count and the same search character.
If there was no previous F, f, T, or t command, it shall be an error.
Repeat
Synopsis:
[count] .
Repeat the last !, <, >, A, C, D, I, J, O, P, R, S, X, Y, a, c, d, i,
o, p, r, s, x, y, or ~ command. It shall be an error if none of these
commands have been executed. Commands (other than commands that enter
text input mode) executed as a result of map expansions, shall not
change the value of the last repeatable command.
Repeated commands with associated motion commands shall repeat the
motion command as well; however, any specified count shall replace the
count(s) that were originally specified to the repeated command or its
associated motion command.
If the motion component of the repeated command is f, F, t, or T, the
repeated command shall not set the remembered search character for the
; and , commands.
If the repeated command is p or P, and the buffer associated with that
command was a numeric buffer named with a number less than 9, the buf‐
fer associated with the repeated command shall be set to be the buffer
named by the name of the previous buffer logically incremented by 1.
If the repeated character is a text input command, the input text asso‐
ciated with that command is repeated literally:
* Input characters are neither macro or abbreviation-expanded.
* Input characters are not interpreted in any special way with the
exception that <newline>, <carriage-return>, and <control>‐T behave
as described in Input Mode Commands in vi.
Current line: Set as described for the repeated command.
Current column: Set as described for the repeated command.
Find Regular Expression
Synopsis:
/
If the input line contains no non-<newline> characters, it shall be
equivalent to a line containing only the last regular expression
encountered. The enhanced regular expressions supported by vi are
described in Regular Expressions in ex.
Otherwise, the line shall be interpreted as one or more regular expres‐
sions, optionally followed by an address offset or a vi z command.
If the regular expression is not the last regular expression on the
line, or if a line offset or z command is specified, the regular
expression shall be terminated by an unescaped '/' character, which
shall not be used as part of the regular expression. If the regular
expression is not the first regular expression on the line, it shall be
preceded by zero or more <blank> characters, a <semicolon>, zero or
more <blank> characters, and a leading '/' character, which shall not
be interpreted as part of the regular expression. It shall be an error
to precede any regular expression with any characters other than these.
Each search shall begin from the character after the first character of
the last match (or, if it is the first search, after the cursor). If
the wrapscan edit option is set, the search shall continue to the char‐
acter before the starting cursor character; otherwise, to the end of
the edit buffer. It shall be an error if any search fails to find a
match, and an informational message to this effect shall be displayed.
An optional address offset (see Addressing in ex) can be specified
after the last regular expression by including a trailing '/' character
after the regular expression and specifying the address offset. This
offset will be from the line containing the match for the last regular
expression specified. It shall be an error if the line offset would
indicate a line address less than 1 or greater than the last line in
the edit buffer. An address offset of zero shall be supported. It shall
be an error to follow the address offset with any other characters than
<blank> characters.
If not used as a motion command, an optional z command (see Redraw Win‐
dow) can be specified after the last regular expression by including a
trailing '/' character after the regular expression, zero or more
<blank> characters, a 'z', zero or more <blank> characters, an optional
new window edit option value, zero or more <blank> characters, and a
location character. The effect shall be as if the z command was exe‐
cuted after the / command. It shall be an error to follow the z command
with any other characters than <blank> characters.
The remembered search direction shall be set to forward.
If used as a motion command:
1. It shall be an error if the last match references the same charac‐
ter in the edit buffer as the starting cursor.
2. If any address offset is specified, the last match shall be
adjusted by the specified offset as described previously.
3. If the starting cursor is after the last match, then the locations
of the starting cursor and the last match in the edit buffer shall
be logically swapped.
4. If any address offset is specified, the text region shall consist
of all lines containing characters from the starting cursor to the
last match line, inclusive, and any text copied to a buffer shall
be in line mode.
5. Otherwise, if the starting line is empty or the starting cursor is
at or before the first non-<blank> non-<newline> of the starting
line, and the last match line is empty or the last match starts at
the first character of the last match line, the text region shall
consist of all lines containing characters from the starting cursor
to the line before the last match line, inclusive, and any text
copied to a buffer shall be in line mode.
6. Otherwise, if the last match line is empty or the last match begins
at a character at or before the first non-<blank> non-<newline> of
the last match line, the region of text shall be from the current
cursor to the last non-<newline> of the line before the last match
line, inclusive, and any text copied to a buffer shall be in char‐
acter mode.
7. Otherwise, the region of text shall be from the current cursor
(inclusive), to the first character of the last match (exclusive),
and any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: If a match is found, set to the last matched line plus
the address offset, if any; otherwise, unchanged.
Current column: Set to the last column on which any portion of the
first character in the last matched string is displayed, if a match is
found; otherwise, unchanged.
Move to First Character in Line
Synopsis:
0 (zero)
Move to the first character on the current line. The character '0'
shall not be interpreted as a command if it is immediately preceded by
a digit.
If used as a motion command:
1. If the cursor character is the first character in the line, it
shall be an error.
2. The text region shall be from the character before the cursor char‐
acter up to and including the first character in the line.
3. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: The last column in which any portion of the first char‐
acter in the line is displayed, or if the line is empty, unchanged.
Execute an ex Command
Synopsis:
:
Execute one or more ex commands.
If any portion of the screen other than the last line of the screen was
overwritten by any ex command (except shell), vi shall display a mes‐
sage indicating that it is waiting for an input from the user, and
shall then read a character. This action may also be taken for other,
unspecified reasons.
If the next character entered is a ':', another ex command shall be
accepted and executed. Any other character shall cause the screen to be
refreshed and vi shall return to command mode.
Current line: As specified for the ex command.
Current column: As specified for the ex command.
Repeat Find
Synopsis:
[count] ;
This command shall be equivalent to the last F, f, T, or t command,
with the specified count, and with the same search character used for
the last F, f, T, or t command. If there was no previous F, f, T, or t
command, it shall be an error.
Shift Left
Synopsis:
[count] < motion
If the motion command is the < command repeated:
1. If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
2. The text region shall be from the current line, up to and including
the next count −1 lines.
Shift any line in the text region specified by the count and motion
command one shiftwidth (see the ex shiftwidth option) toward the start
of the line, as described by the ex < command. The unshifted lines
shall be copied to the unnamed buffer in line mode.
Current line: If the motion was from the current cursor position toward
the end of the edit buffer, unchanged. Otherwise, set to the first line
in the edit buffer that is part of the text region specified by the
motion command.
Current column: Set to non-<blank>.
Shift Right
Synopsis:
[count] > motion
If the motion command is the > command repeated:
1. If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
2. The text region shall be from the current line, up to and including
the next count −1 lines.
Shift any line with characters in the text region specified by the
count and motion command one shiftwidth (see the ex shiftwidth option)
away from the start of the line, as described by the ex > command. The
unshifted lines shall be copied into the unnamed buffer in line mode.
Current line: If the motion was from the current cursor position toward
the end of the edit buffer, unchanged. Otherwise, set to the first line
in the edit buffer that is part of the text region specified by the
motion command.
Current column: Set to non-<blank>.
Scan Backwards for Regular Expression
Synopsis:
?
Scan backwards; the ? command shall be equivalent to the / command
(see Find Regular Expression) with the following exceptions:
1. The input prompt shall be a '?'.
2. Each search shall begin from the character before the first charac‐
ter of the last match (or, if it is the first search, the character
before the cursor character).
3. The search direction shall be from the cursor toward the beginning
of the edit buffer, and the wrapscan edit option shall affect
whether the search wraps to the end of the edit buffer and contin‐
ues.
4. The remembered search direction shall be set to backward.
Execute
Synopsis:
@buffer
If the buffer is specified as @, the last buffer executed shall be
used. If no previous buffer has been executed, it shall be an error.
Behave as if the contents of the named buffer were entered as standard
input. After each line of a line-mode buffer, and all but the last line
of a character mode buffer, behave as if a <newline> were entered as
standard input.
If an error occurs during this process, an error message shall be writ‐
ten, and no more characters resulting from the execution of this com‐
mand shall be processed.
If a count is specified, behave as if that count were entered as user
input before the characters from the @ buffer were entered.
Current line: As specified for the individual commands.
Current column: As specified for the individual commands.
Reverse Case
Synopsis:
[count] ~
Reverse the case of the current character and the next count −1 charac‐
ters, such that lowercase characters that have uppercase counterparts
shall be changed to uppercase characters, and uppercase characters that
have lowercase counterparts shall be changed to lowercase characters,
as prescribed by the current locale. No other characters shall be
affected by this command.
If there are less than count −1 characters after the cursor in the edit
buffer, count shall be adjusted to the number of characters after the
cursor in the edit buffer minus 1.
For the purposes of this command, the next character after the last
non-<newline> on the line shall be the next character in the edit buf‐
fer.
Current line: Set to the line including the (count−1)th character after
the cursor.
Current column: Set to the last column in which any portion of the
(count−1)th character after the cursor is displayed.
Append
Synopsis:
[count] a
Enter text input mode after the current cursor position. No characters
already in the edit buffer shall be affected by this command. A count
shall cause the input text to be appended count −1 more times to the
end of the input.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Append at End-of-Line
Synopsis:
[count] A
This command shall be equivalent to the vi command:
$ [ count ] a
(see Append).
Move Backward to Preceding Word
Synopsis:
[count] b
With the exception that words are used as the delimiter instead of big‐
words, this command shall be equivalent to the B command.
Move Backward to Preceding Bigword
Synopsis:
[count] B
If the edit buffer is empty or the cursor is on the first character of
the edit buffer, it shall be an error. If less than count bigwords
begin between the cursor and the start of the edit buffer, count shall
be adjusted to the number of bigword beginnings between the cursor and
the start of the edit buffer.
If used as a motion command:
1. The text region shall be from the first character of the countth
previous bigword beginning up to but not including the cursor char‐
acter.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line containing the current column.
Current column: Set to the last column upon which any part of the first
character of the countth previous bigword is displayed.
Change
Synopsis:
[buffer][count] c motion
If the motion command is the c command repeated:
1. The buffer text shall be in line mode.
2. If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
3. The text region shall be from the current line up to and including
the next count −1 lines.
Otherwise, the buffer text mode and text region shall be as specified
by the motion command.
The replaced text shall be copied into buffer, if specified, and into
the unnamed buffer. If the text to be replaced contains characters from
more than a single line, or the buffer text is in line mode, the
replaced text shall be copied into the numeric buffers as well.
If the buffer text is in line mode:
1. Any lines that contain characters in the region shall be deleted,
and the editor shall enter text input mode at the beginning of a
new line which shall replace the first line deleted.
2. If the autoindent edit option is set, autoindent characters equal
to the autoindent characters on the first line deleted shall be
inserted as if entered by the user.
Otherwise, if characters from more than one line are in the region of
text:
1. The text shall be deleted.
2. Any text remaining in the last line in the text region shall be
appended to the first line in the region, and the last line in the
region shall be deleted.
3. The editor shall enter text input mode after the last character not
deleted from the first line in the text region, if any; otherwise,
on the first column of the first line in the region.
Otherwise:
1. If the glyph for '$' is smaller than the region, the end of the
region shall be marked with a '$'.
2. The editor shall enter text input mode, overwriting the region of
text.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Change to End-of-Line
Synopsis:
[buffer][count] C
This command shall be equivalent to the vi command:
[buffer][count] c$
See the c command.
Delete
Synopsis:
[buffer][count] d motion
If the motion command is the d command repeated:
1. The buffer text shall be in line mode.
2. If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
3. The text region shall be from the current line up to and including
the next count −1 lines.
Otherwise, the buffer text mode and text region shall be as specified
by the motion command.
If in open mode, and the current line is deleted, and the line remains
on the display, an '@' character shall be displayed as the first glyph
of that line.
Delete the region of text into buffer, if specified, and into the
unnamed buffer. If the text to be deleted contains characters from more
than a single line, or the buffer text is in line mode, the deleted
text shall be copied into the numeric buffers, as well.
Current line: Set to the first text region line that appears in the
edit buffer, unless that line has been deleted, in which case it shall
be set to the last line in the edit buffer, or line 1 if the edit buf‐
fer is empty.
Current column:
1. If the line is empty, set to column position 1.
2. Otherwise, if the buffer text is in line mode or the motion was
from the cursor toward the end of the edit buffer:
a. If a character from the current line is displayed in the cur‐
rent column, set to the last column that displays any portion
of that character.
b. Otherwise, set to the last column in which any portion of any
character in the line is displayed.
3. Otherwise, if a character is displayed in the column that began the
text region, set to the last column that displays any portion of
that character.
4. Otherwise, set to the last column in which any portion of any char‐
acter in the line is displayed.
Delete to End-of-Line
Synopsis:
[buffer] D
Delete the text from the current position to the end of the current
line; equivalent to the vi command:
[buffer] d$
Move to End-of-Word
Synopsis:
[count] e
With the exception that words are used instead of bigwords as the
delimiter, this command shall be equivalent to the E command.
Move to End-of-Bigword
Synopsis:
[count] E
If the edit buffer is empty it shall be an error. If less than count
bigwords end between the cursor and the end of the edit buffer, count
shall be adjusted to the number of bigword endings between the cursor
and the end of the edit buffer.
If used as a motion command:
1. The text region shall be from the last character of the countth
next bigword up to and including the cursor character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Set to the line containing the current column.
Current column: Set to the last column upon which any part of the last
character of the countth next bigword is displayed.
Find Character in Current Line (Forward)
Synopsis:
[count] f character
It shall be an error if count occurrences of the character do not occur
after the cursor in the line.
If used as a motion command:
1. The text range shall be from the cursor character up to and includ‐
ing the countth occurrence of the specified character after the
cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
countth occurrence of the specified character after the cursor appears
in the line.
Find Character in Current Line (Reverse)
Synopsis:
[count] F character
It shall be an error if count occurrences of the character do not occur
before the cursor in the line.
If used as a motion command:
1. The text region shall be from the countth occurrence of the speci‐
fied character before the cursor, up to, but not including the cur‐
sor character.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
countth occurrence of the specified character before the cursor appears
in the line.
Move to Line
Synopsis:
[count] G
If count is not specified, it shall default to the last line of the
edit buffer. If count is greater than the last line of the edit buf‐
fer, it shall be an error.
If used as a motion command:
1. The text region shall be from the cursor line up to and including
the specified line.
2. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
Current line: Set to count if count is specified; otherwise, the last
line.
Current column: Set to non-<blank>.
Move to Top of Screen
Synopsis:
[count] H
If the beginning of the line count greater than the first line of which
any portion appears on the display does not exist, it shall be an
error.
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall be from the starting line up to
and including (the first line of the display + count −1).
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
Otherwise, it shall set the current line and current column as follows.
Current line: Set to (the first line of the display + count −1).
Current column: Set to non-<blank>.
Insert Before Cursor
Synopsis:
[count] i
Enter text input mode before the current cursor position. No characters
already in the edit buffer shall be affected by this command. A count
shall cause the input text to be appended count −1 more times to the
end of the input.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Insert at Beginning of Line
Synopsis:
[count] I
This command shall be equivalent to the vi command ^[count]i.
Join
Synopsis:
[count] J
If the current line is the last line in the edit buffer, it shall be an
error.
This command shall be equivalent to the ex join command with no
addresses, and an ex command count value of 1 if count was not speci‐
fied or if a count of 1 was specified, and an ex command count value of
count −1 for any other value of count, except that the current line and
column shall be set as follows.
Current line: Unchanged.
Current column: The last column in which any portion of the character
following the last character in the initial line is displayed, or the
last non-<newline> in the line if no characters were appended.
Move to Bottom of Screen
Synopsis:
[count] L
If the beginning of the line count less than the last line of which any
portion appears on the display does not exist, it shall be an error.
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall include all lines from the start‐
ing cursor line to (the last line of the display −(count −1)).
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
1. If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
2. Otherwise, it shall set the current line and current column as fol‐
lows.
Current line: Set to (the last line of the display −(count −1)).
Current column: Set to non-<blank>.
Mark Position
Synopsis:
m letter
This command shall be equivalent to the ex mark command with the speci‐
fied character as an argument.
Move to Middle of Screen
Synopsis:
M
The middle line of the display shall be calculated as follows:
(the top line of the display) + (((number of lines displayed) +1) /2) −1
If used as a motion command:
1. If in open mode, the text region shall be the current line.
2. Otherwise, the text region shall include all lines from the start‐
ing cursor line up to and including the middle line of the display.
3. Any text copied to a buffer shall be in line mode.
If not used as a motion command:
If in open mode, this command shall set the current column to
non-<blank> and do nothing else.
Otherwise, it shall set the current line and current column as follows.
Current line: Set to the middle line of the display.
Current column: Set to non-<blank>.
Repeat Regular Expression Find (Forward)
Synopsis:
n
If the remembered search direction was forward, the n command shall be
equivalent to the vi / command with no characters entered by the user.
Otherwise, it shall be equivalent to the vi ? command with no charac‐
ters entered by the user.
If the n command is used as a motion command for the ! command, the
editor shall not enter text input mode on the last line on the screen,
and shall behave as if the user entered a single '!' character as the
text input.
Repeat Regular Expression Find (Reverse)
Synopsis:
N
Scan for the next match of the last pattern given to / or ?, but in the
reverse direction; this is the reverse of n.
If the remembered search direction was forward, the N command shall be
equivalent to the vi ? command with no characters entered by the user.
Otherwise, it shall be equivalent to the vi / command with no charac‐
ters entered by the user. If the N command is used as a motion command
for the ! command, the editor shall not enter text input mode on the
last line on the screen, and shall behave as if the user entered a sin‐
gle ! character as the text input.
Insert Empty Line Below
Synopsis:
o
Enter text input mode in a new line appended after the current line. A
count shall cause the input text to be appended count −1 more times to
the end of the already added text, each time starting on a new,
appended line.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Insert Empty Line Above
Synopsis:
O
Enter text input mode in a new line inserted before the current line. A
count shall cause the input text to be appended count −1 more times to
the end of the already added text, each time starting on a new,
appended line.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Put from Buffer Following
Synopsis:
[buffer] p
If no buffer is specified, the unnamed buffer shall be used.
If the buffer text is in line mode, the text shall be appended below
the current line, and each line of the buffer shall become a new line
in the edit buffer. A count shall cause the buffer text to be appended
count −1 more times to the end of the already added text, each time
starting on a new, appended line.
If the buffer text is in character mode, the text shall be appended
into the current line after the cursor, and each line of the buffer
other than the first and last shall become a new line in the edit buf‐
fer. A count shall cause the buffer text to be appended count −1 more
times to the end of the already added text, each time starting after
the last added character.
Current line: If the buffer text is in line mode, set the line to line
+1; otherwise, unchanged.
Current column: If the buffer text is in line mode:
1. If there is a non-<blank> in the first line of the buffer, set to
the last column on which any portion of the first non-<blank> in
the line is displayed.
2. If there is no non-<blank> in the first line of the buffer, set to
the last column on which any portion of the last non-<newline> in
the first line of the buffer is displayed.
If the buffer text is in character mode:
1. If the text in the buffer is from more than a single line, then set
to the last column on which any portion of the first character from
the buffer is displayed.
2. Otherwise, if the buffer is the unnamed buffer, set to the last
column on which any portion of the last character from the buffer
is displayed.
3. Otherwise, set to the first column on which any portion of the
first character from the buffer is displayed.
Put from Buffer Before
Synopsis:
[buffer] P
If no buffer is specified, the unnamed buffer shall be used.
If the buffer text is in line mode, the text shall be inserted above
the current line, and each line of the buffer shall become a new line
in the edit buffer. A count shall cause the buffer text to be appended
count −1 more times to the end of the already added text, each time
starting on a new, appended line.
If the buffer text is in character mode, the text shall be inserted
into the current line before the cursor, and each line of the buffer
other than the first and last shall become a new line in the edit buf‐
fer. A count shall cause the buffer text to be appended count −1 more
times to the end of the already added text, each time starting after
the last added character.
Current line: Unchanged.
Current column: If the buffer text is in line mode:
1. If there is a non-<blank> in the first line of the buffer, set to
the last column on which any portion of that character is dis‐
played.
2. If there is no non-<blank> in the first line of the buffer, set to
the last column on which any portion of the last non-<newline> in
the first line of the buffer is displayed.
If the buffer text is in character mode:
1. If the text in the buffer is from more than a single line, then set
to the last column on which any portion of the first character from
the buffer is displayed.
2. Otherwise, if the buffer is the unnamed buffer, set to the last
column on which any portion of the last character from the buffer
is displayed.
3. Otherwise, set to the first column on which any portion of the
first character from the buffer is displayed.
Enter ex Mode
Synopsis:
Q
Leave visual or open mode and enter ex command mode.
Current line: Unchanged.
Current column: Unchanged.
Replace Character
Synopsis:
[count] r character
Replace the count characters at and after the cursor with the specified
character. If there are less than count non-<newline> characters at and
after the cursor on the line, it shall be an error.
If character is <control>‐V, any next character other than the <new‐
line> shall be stripped of any special meaning and used as a literal
character.
If character is <ESC>, no replacement shall be made and the current
line and current column shall be unchanged.
If character is <carriage-return> or <newline>, count new lines shall
be appended to the current line. All but the last of these lines shall
be empty. count characters at and after the cursor shall be discarded,
and any remaining characters after the cursor in the current line shall
be moved to the last of the new lines. If the autoindent edit option is
set, they shall be preceded by the same number of autoindent characters
found on the line from which the command was executed.
Current line: Unchanged unless the replacement character is a <car‐
riage-return> or <newline>, in which case it shall be set to line +
count.
Current column: Set to the last column position on which a portion of
the last replaced character is displayed, or if the replacement charac‐
ter caused new lines to be created, set to non-<blank>.
Replace Characters
Synopsis:
R
Enter text input mode at the current cursor position possibly replacing
text on the current line. A count shall cause the input text to be
appended count −1 more times to the end of the input.
Current line/column: As specified for the text input commands (see
Input Mode Commands in vi).
Substitute Character
Synopsis:
[buffer][count] s
This command shall be equivalent to the vi command:
[buffer][count] c<space>
Substitute Lines
Synopsis:
[buffer][count] S
This command shall be equivalent to the vi command:
[buffer][count] c_
Move Cursor to Before Character (Forward)
Synopsis:
[count] t character
It shall be an error if count occurrences of the character do not occur
after the cursor in the line.
If used as a motion command:
1. The text region shall be from the cursor up to but not including
the countth occurrence of the specified character after the cursor.
2. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
character before the countth occurrence of the specified character
after the cursor appears in the line.
Move Cursor to After Character (Reverse)
Synopsis:
[count] T character
It shall be an error if count occurrences of the character do not occur
before the cursor in the line.
If used as a motion command:
1. If the character before the cursor is the specified character, it
shall be an error.
2. The text region shall be from the character before the cursor up to
but not including the countth occurrence of the specified character
before the cursor.
3. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
Current line: Unchanged.
Current column: Set to the last column in which any portion of the
character after the countth occurrence of the specified character
before the cursor appears in the line.
Undo
Synopsis:
u
This command shall be equivalent to the ex undo command except that the
current line and current column shall be set as follows:
Current line: Set to the first line added or changed if any; otherwise,
move to the line preceding any deleted text if one exists; otherwise,
move to line 1.
Current column: If undoing an ex command, set to the first non-<blank>.
Otherwise, if undoing a text input command:
1. If the command was a C, c, O, o, R, S, or s command, the current
column shall be set to the value it held when the text input com‐
mand was entered.
2. Otherwise, set to the last column in which any portion of the first
character after the deleted text is displayed, or, if no non-<new‐
line> characters follow the text deleted from this line, set to the
last column in which any portion of the last non-<newline> in the
line is displayed, or 1 if the line is empty.
Otherwise, if a single line was modified (that is, not added or
deleted) by the u command:
1. If text was added or changed, set to the last column in which any
portion of the first character added or changed is displayed.
2. If text was deleted, set to the last column in which any portion of
the first character after the deleted text is displayed, or, if no
non-<newline> characters follow the deleted text, set to the last
column in which any portion of the last non-<newline> in the line
is displayed, or 1 if the line is empty.
Otherwise, set to non-<blank>.
Undo Current Line
Synopsis:
U
Restore the current line to its state immediately before the most
recent time that it became the current line.
Current line: Unchanged.
Current column: Set to the first column in the line in which any por‐
tion of the first character in the line is displayed.
Move to Beginning of Word
Synopsis:
[count] w
With the exception that words are used as the delimiter instead of big‐
words, this command shall be equivalent to the W command.
Move to Beginning of Bigword
Synopsis:
[count] W
If the edit buffer is empty, it shall be an error. If there are less
than count bigwords between the cursor and the end of the edit buffer,
count shall be adjusted to move the cursor to the last bigword in the
edit buffer.
If used as a motion command:
1. If the associated command is c, count is 1, and the cursor is on a
<blank>, the region of text shall be the current character and no
further action shall be taken.
2. If there are less than count bigwords between the cursor and the
end of the edit buffer, then the command shall succeed, and the
region of text shall include the last character of the edit buffer.
3. If there are <blank> characters or an end-of-line that precede the
countth bigword, and the associated command is c, the region of
text shall be up to and including the last character before the
preceding <blank> characters or end-of-line.
4. If there are <blank> characters or an end-of-line that precede the
bigword, and the associated command is d or y, the region of text
shall be up to and including the last <blank> before the start of
the bigword or end-of-line.
5. Any text copied to a buffer shall be in character mode.
If not used as a motion command:
1. If the cursor is on the last character of the edit buffer, it shall
be an error.
Current line: Set to the line containing the current column.
Current column: Set to the last column in which any part of the first
character of the countth next bigword is displayed.
Delete Character at Cursor
Synopsis:
[buffer][count] x
Delete the count characters at and after the current character into
buffer, if specified, and into the unnamed buffer.
If the line is empty, it shall be an error. If there are less than
count non-<newline> characters at and after the cursor on the current
line, count shall be adjusted to the number of non-<newline> characters
at and after the cursor.
Current line: Unchanged.
Current column: If the line is empty, set to column position 1. Other‐
wise, if there were count or less non-<newline> characters at and after
the cursor on the current line, set to the last column that displays
any part of the last non-<newline> of the line. Otherwise, unchanged.
Delete Character Before Cursor
Synopsis:
[buffer][count] X
Delete the count characters before the current character into buffer,
if specified, and into the unnamed buffer.
If there are no characters before the current character on the current
line, it shall be an error. If there are less than count previous char‐
acters on the current line, count shall be adjusted to the number of
previous characters on the line.
Current line: Unchanged.
Current column: Set to (current column − the width of the deleted char‐
acters).
Yank
Synopsis:
[buffer][count] y motion
Copy (yank) the region of text into buffer, if specified, and into the
unnamed buffer.
If the motion command is the y command repeated:
1. The buffer shall be in line mode.
2. If there are less than count −1 lines after the current line in the
edit buffer, it shall be an error.
3. The text region shall be from the current line up to and including
the next count −1 lines.
Otherwise, the buffer text mode and text region shall be as specified
by the motion command.
Current line: If the motion was from the current cursor position toward
the end of the edit buffer, unchanged. Otherwise, set to the first line
in the edit buffer that is part of the text region specified by the
motion command.
Current column:
1. If the motion was from the current cursor position toward the end
of the edit buffer, unchanged.
2. Otherwise, if the current line is empty, set to column position 1.
3. Otherwise, set to the last column that displays any part of the
first character in the file that is part of the text region speci‐
fied by the motion command.
Yank Current Line
Synopsis:
[buffer][count] Y
This command shall be equivalent to the vi command:
[buffer][count] y_
Redraw Window
If in open mode, the z command shall have the Synopsis:
Synopsis:
[count] z
If count is not specified, it shall default to the window edit option
−1. The z command shall be equivalent to the ex z command, with a type
character of = and a count of count −2, except that the current line
and current column shall be set as follows, and the window edit option
shall not be affected. If the calculation for the count argument would
result in a negative number, the count argument to the ex z command
shall be zero. A blank line shall be written after the last line is
written.
Current line: Unchanged.
Current column: Unchanged.
If not in open mode, the z command shall have the following Synopsis:
Synopsis:
[line] z [count] character
If line is not specified, it shall default to the current line. If line
is specified, but is greater than the number of lines in the edit buf‐
fer, it shall default to the number of lines in the edit buffer.
If count is specified, the value of the window edit option shall be set
to count (as described in the ex window command), and the screen shall
be redrawn.
line shall be placed as specified by the following characters:
<newline>, <carriage-return>
Place the beginning of the line on the first line of the display.
. Place the beginning of the line in the center of the display. The
middle line of the display shall be calculated as described for
the M command.
− Place an unspecified portion of the line on the last line of the
display.
+ If line was specified, equivalent to the <newline> case. If line
was not specified, display a screen where the first line of the
display shall be (current last line) +1. If there are no lines
after the last line in the display, it shall be an error.
^ If line was specified, display a screen where the last line of
the display shall contain an unspecified portion of the first
line of a display that had an unspecified portion of the speci‐
fied line on the last line of the display. If this calculation
results in a line before the beginning of the edit buffer, dis‐
play the first screen of the edit buffer.
Otherwise, display a screen where the last line of the display
shall contain an unspecified portion of (current first line −1).
If this calculation results in a line before the beginning of the
edit buffer, it shall be an error.
Current line: If line and the '^' character were specified:
1. If the first screen was displayed as a result of the command
attempting to display lines before the beginning of the edit buf‐
fer: if the first screen was already displayed, unchanged; other‐
wise, set to (current first line −1).
2. Otherwise, set to the last line of the display.
If line and the '+' character were specified, set to the first line of
the display.
Otherwise, if line was specified, set to line.
Otherwise, unchanged.
Current column: Set to non-<blank>.
Exit
Synopsis:
ZZ
This command shall be equivalent to the ex xit command with no
addresses, trailing !, or filename (see the ex xit command).
Input Mode Commands in vi
In text input mode, the current line shall consist of zero or more of
the following categories, plus the terminating <newline>:
1. Characters preceding the text input entry point
Characters in this category shall not be modified during text input
mode.
2. autoindent characters
autoindent characters shall be automatically inserted into each
line that is created in text input mode, either as a result of
entering a <newline> or <carriage-return> while in text input mode,
or as an effect of the command itself; for example, O or o (see the
ex autoindent command), as if entered by the user.
It shall be possible to erase autoindent characters with the <con‐
trol>‐D command; it is unspecified whether they can be erased by
<control>‐H, <control>‐U, and <control>‐W characters. Erasing any
autoindent character turns the glyph into erase-columns and deletes
the character from the edit buffer, but does not change its repre‐
sentation on the screen.
3. Text input characters
Text input characters are the characters entered by the user. Eras‐
ing any text input character turns the glyph into erase-columns and
deletes the character from the edit buffer, but does not change its
representation on the screen.
Each text input character entered by the user (that does not have a
special meaning) shall be treated as follows:
a. The text input character shall be appended to the last charac‐
ter in the edit buffer from the first, second, or third cate‐
gories.
b. If there are no erase-columns on the screen, the text input
command was the R command, and characters in the fifth category
from the original line follow the cursor, the next such charac‐
ter shall be deleted from the edit buffer. If the slowopen edit
option is not set, the corresponding glyph on the screen shall
become erase-columns.
c. If there are erase-columns on the screen, as many columns as
they occupy, or as are necessary, shall be overwritten to dis‐
play the text input character. (If only part of a multi-column
glyph is overwritten, the remainder shall be left on the
screen, and continue to be treated as erase-columns; it is
unspecified whether the remainder of the glyph is modified in
any way.)
d. If additional display line columns are needed to display the
text input character:
i. If the slowopen edit option is set, the text input charac‐
ters shall be displayed on subsequent display line col‐
umns, overwriting any characters displayed in those col‐
umns.
ii. Otherwise, any characters currently displayed on or after
the column on the display line where the text input char‐
acter is to be displayed shall be pushed ahead the number
of display line columns necessary to display the rest of
the text input character.
4. Erase-columns
Erase-columns are not logically part of the edit buffer, appearing
only on the screen, and may be overwritten on the screen by subse‐
quent text input characters. When text input mode ends, all erase-
columns shall no longer appear on the screen.
Erase-columns are initially the region of text specified by the c
command (see Change); however, erasing autoindent or text input
characters causes the glyphs of the erased characters to be treated
as erase-columns.
5. Characters following the text region for the c command, or the text
input entry point for all other commands
Characters in this category shall not be modified during text input
mode, except as specified in category 3.b. for the R text input
command, or as <blank> characters deleted when a <newline> or <car‐
riage-return> is entered.
It is unspecified whether it is an error to attempt to erase past the
beginning of a line that was created by the entry of a <newline> or
<carriage-return> during text input mode. If it is not an error, the
editor shall behave as if the erasing character was entered immediately
after the last text input character entered on the previous line, and
all of the non-<newline> characters on the current line shall be
treated as erase-columns.
When text input mode is entered, or after a text input mode character
is entered (except as specified for the special characters below), the
cursor shall be positioned as follows:
1. On the first column that displays any part of the first erase-col‐
umn, if one exists
2. Otherwise, if the slowopen edit option is set, on the first display
line column after the last character in the first, second, or third
categories, if one exists
3. Otherwise, the first column that displays any part of the first
character in the fifth category, if one exists
4. Otherwise, the display line column after the last character in the
first, second, or third categories, if one exists
5. Otherwise, on column position 1
The characters that are updated on the screen during text input mode
are unspecified, other than that the last text input character shall
always be updated, and, if the slowopen edit option is not set, the
current cursor character shall always be updated.
The following specifications are for command characters entered during
text input mode.
NUL
Synopsis:
NUL
If the first character of the text input is a NUL, the most recently
input text shall be input as if entered by the user, and then text
input mode shall be exited. The text shall be input literally; that is,
characters are neither macro or abbreviation expanded, nor are any
characters interpreted in any special manner. It is unspecified whether
implementations shall support more than 256 bytes of remembered input
text.
<control>-D
Synopsis:
<control>-D
The <control>‐D character shall have no special meaning when in text
input mode for a line-oriented command (see Command Descriptions in
vi).
This command need not be supported on block-mode terminals.
If the cursor does not follow an autoindent character, or an autoindent
character and a '0' or '^' character:
1. If the cursor is in column position 1, the <control>‐D character
shall be discarded and no further action taken.
2. Otherwise, the <control>‐D character shall have no special meaning.
If the last input character was a '0', the cursor shall be moved to
column position 1.
Otherwise, if the last input character was a '^', the cursor shall be
moved to column position 1. In addition, the autoindent level for the
next input line shall be derived from the same line from which the
autoindent level for the current input line was derived.
Otherwise, the cursor shall be moved back to the column after the pre‐
vious shiftwidth (see the ex shiftwidth command) boundary.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns as
described in Input Mode Commands in vi.
Current line: Unchanged.
Current column: Set to 1 if the <control>‐D was preceded by a '^' or
'0'; otherwise, set to (column −1) −((column −2) % shiftwidth).
<control>-H
Synopsis:
<control>-H
If in text input mode for a line-oriented command, and there are no
characters to erase, text input mode shall be terminated, no further
action shall be done for this command, and the current line and column
shall be unchanged.
If there are characters other than autoindent characters that have been
input on the current line before the cursor, the cursor shall move back
one character.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the <control>‐H
command is an error or if the cursor moves back one autoindent charac‐
ter.
Otherwise, if the cursor is in column position 1 and there are previous
lines that have been input, it is implementation-defined whether the
<control>‐H command is an error or if it is equivalent to entering
<control>‐H after the last input character on the previous input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns as
described in Input Mode Commands in vi.
The current erase character (see stty) shall cause an equivalent action
to the <control>‐H command, unless the previously inserted character
was a <backslash>, in which case it shall be as if the literal current
erase character had been inserted instead of the <backslash>.
Current line: Unchanged, unless previously input lines are erased, in
which case it shall be set to line −1.
Current column: Set to the first column that displays any portion of
the character backed up over.
<newline>
Synopsis:
<newline>
<carriage-return>
<control>-J
<control>-M
If input was part of a line-oriented command, text input mode shall be
terminated and the command shall continue execution with the input pro‐
vided.
Otherwise, terminate the current line. If there are no characters other
than autoindent characters on the line, all characters on the line
shall be discarded. Otherwise, it is unspecified whether the autoin‐
dent characters in the line are modified by entering these characters.
Continue text input mode on a new line appended after the current line.
If the slowopen edit option is set, the lines on the screen below the
current line shall not be pushed down, but the first of them shall be
cleared and shall appear to be overwritten. Otherwise, the lines of the
screen below the current line shall be pushed down.
If the autoindent edit option is set, an appropriate number of autoin‐
dent characters shall be added as a prefix to the line as described by
the ex autoindent edit option.
All columns after the cursor that are erase-columns (as described in
Input Mode Commands in vi) shall be discarded.
If the autoindent edit option is set, all <blank> characters immedi‐
ately following the cursor shall be discarded.
All remaining characters after the cursor shall be transferred to the
new line, positioned after any autoindent characters.
Current line: Set to current line +1.
Current column: Set to the first column that displays any portion of
the first character after the autoindent characters on the new line, if
any, or the first column position after the last autoindent character,
if any, or column position 1.
<control>-T
Synopsis:
<control>-T
The <control>‐T character shall have no special meaning when in text
input mode for a line-oriented command (see Command Descriptions in
vi).
This command need not be supported on block-mode terminals.
Behave as if the user entered the minimum number of <blank> characters
necessary to move the cursor forward to the column position after the
next shiftwidth (see the ex shiftwidth command) boundary.
Current line: Unchanged.
Current column: Set to column + shiftwidth − ((column −1) %
shiftwidth).
<control>-U
Synopsis:
<control>-U
If there are characters other than autoindent characters that have been
input on the current line before the cursor, the cursor shall move to
the first character input after the autoindent characters.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the <control>‐U
command is an error or if the cursor moves to the first column position
on the line.
Otherwise, if the cursor is in column position 1 and there are previous
lines that have been input, it is implementation-defined whether the
<control>‐U command is an error or if it is equivalent to entering
<control>‐U after the last input character on the previous input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns as
described in Input Mode Commands in vi.
The current kill character (see stty) shall cause an equivalent action
to the <control>‐U command, unless the previously inserted character
was a <backslash>, in which case it shall be as if the literal current
kill character had been inserted instead of the <backslash>.
Current line: Unchanged, unless previously input lines are erased, in
which case it shall be set to line −1.
Current column: Set to the first column that displays any portion of
the last character backed up over.
<control>-V
Synopsis:
<control>-V
<control>-Q
Allow the entry of any subsequent character, other than <control>‐J or
the <newline>, as a literal character, removing any special meaning
that it may have to the editor in text input mode. If a <control>‐V or
<control>‐Q is entered before a <control>‐J or <newline>, the <con‐
trol>‐V or <control>‐Q character shall be discarded, and the <con‐
trol>‐J or <newline> shall behave as described in the <newline> command
character during input mode.
For purposes of the display only, the editor shall behave as if a '^'
character was entered, and the cursor shall be positioned as if over‐
writing the '^' character. When a subsequent character is entered, the
editor shall behave as if that character was entered instead of the
original <control>‐V or <control>‐Q character.
Current line: Unchanged.
Current column: Unchanged.
<control>-W
Synopsis:
<control>-W
If there are characters other than autoindent characters that have been
input on the current line before the cursor, the cursor shall move back
over the last word preceding the cursor (including any <blank> charac‐
ters between the end of the last word and the current cursor); the cur‐
sor shall not move to before the first character after the end of any
autoindent characters.
Otherwise, if there are autoindent characters on the current line
before the cursor, it is implementation-defined whether the <control>‐W
command is an error or if the cursor moves to the first column position
on the line.
Otherwise, if the cursor is in column position 1 and there are previous
lines that have been input, it is implementation-defined whether the
<control>‐W command is an error or if it is equivalent to entering
<control>‐W after the last input character on the previous input line.
Otherwise, it shall be an error.
All of the glyphs on columns between the starting cursor position and
(inclusively) the ending cursor position shall become erase-columns as
described in Input Mode Commands in vi.
Current line: Unchanged, unless previously input lines are erased, in
which case it shall be set to line −1.
Current column: Set to the first column that displays any portion of
the last character backed up over.
<ESC>
Synopsis:
<ESC>
If input was part of a line-oriented command:
1. If interrupt was entered, text input mode shall be terminated and
the editor shall return to command mode. The terminal shall be
alerted.
2. If <ESC> was entered, text input mode shall be terminated and the
command shall continue execution with the input provided.
Otherwise, terminate text input mode and return to command mode.
Any autoindent characters entered on newly created lines that have no
other non-<newline> characters shall be deleted.
Any leading autoindent and <blank> characters on newly created lines
shall be rewritten to be the minimum number of <blank> characters pos‐
sible.
The screen shall be redisplayed as necessary to match the contents of
the edit buffer.
Current line: Unchanged.
Current column:
1. If there are text input characters on the current line, the column
shall be set to the last column where any portion of the last text
input character is displayed.
2. Otherwise, if a character is displayed in the current column,
unchanged.
3. Otherwise, set to column position 1.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
When any error is encountered and the standard input is not a terminal
device file, vi shall not write the file or return to command or text
input mode, and shall terminate with a non-zero exit status.
Otherwise, when an unrecoverable error is encountered it shall be
equivalent to a SIGHUP asynchronous event.
Otherwise, when an error is encountered, the editor shall behave as
specified in Command Descriptions in vi.
The following sections are informative.
APPLICATION USAGE
None.
EXAMPLES
None.
RATIONALE
See the RATIONALE for ex for more information on vi. Major portions of
the vi utility specification point to ex to avoid inadvertent diver‐
gence. While ex and vi have historically been implemented as a single
utility, this is not required by POSIX.1‐2008.
It is recognized that portions of vi would be difficult, if not impos‐
sible, to implement satisfactorily on a block-mode terminal, or a ter‐
minal without any form of cursor addressing, thus it is not a mandatory
requirement that such features should work on all terminals. It is the
intention, however, that a vi implementation should provide the full
set of capabilities on all terminals capable of supporting them.
Historically, vi exited immediately if the standard input was not a
terminal. POSIX.1‐2008 permits, but does not require, this behavior. An
end-of-file condition is not equivalent to an end-of-file character. A
common end-of-file character, <control>‐D, is historically a vi com‐
mand.
The text in the STDOUT section reflects the usage of the verb display
in this section; some implementations of vi use standard output to
write to the terminal, but POSIX.1‐2008 does not require that to be the
case.
Historically, implementations reverted to open mode if the terminal was
incapable of supporting full visual mode. POSIX.1‐2008 requires this
behavior. Historically, the open mode of vi behaved roughly equiva‐
lently to the visual mode, with the exception that only a single line
from the edit buffer (one ``buffer line'') was kept current at any
time. This line was normally displayed on the next-to-last line of a
terminal with cursor addressing (and the last line performed its normal
visual functions for line-oriented commands and messages). In addition,
some few commands behaved differently in open mode than in visual mode.
POSIX.1‐2008 requires conformance to historical practice.
Historically, ex and vi implementations have expected text to proceed
in the usual European/Latin order of left to right, top to bottom.
There is no requirement in POSIX.1‐2008 that this be the case. The
specification was deliberately written using words like ``before'',
``after'', ``first'', and ``last'' in order to permit implementations
to support the natural text order of the language.
Historically, lines past the end of the edit buffer were marked with
single <tilde> ('~') characters; that is, if the one-based display was
20 lines in length, and the last line of the file was on line one, then
lines 2-20 would contain only a single '~' character.
Historically, the vi editor attempted to display only complete lines at
the bottom of the screen (it did display partial lines at the top of
the screen). If a line was too long to fit in its entirety at the bot‐
tom of the screen, the screen lines where the line would have been dis‐
played were displayed as single '@' characters, instead of displaying
part of the line. POSIX.1‐2008 permits, but does not require, this
behavior. Implementations are encouraged to attempt always to display a
complete line at the bottom of the screen when doing scrolling or
screen positioning by buffer lines.
Historically, lines marked with '@' were also used to minimize output
to dumb terminals over slow lines; that is, changes local to the cursor
were updated, but changes to lines on the screen that were not close to
the cursor were simply marked with an '@' sign instead of being updated
to match the current text. POSIX.1‐2008 permits, but does not require
this feature because it is used ever less frequently as terminals
become smarter and connections are faster.
Initialization in ex and vi
Historically, vi always had a line in the edit buffer, even if the edit
buffer was ``empty''. For example:
1. The ex command = executed from visual mode wrote ``1'' when the
buffer was empty.
2. Writes from visual mode of an empty edit buffer wrote files of a
single character (a <newline>), while writes from ex mode of an
empty edit buffer wrote empty files.
3. Put and read commands into an empty edit buffer left an empty line
at the top of the edit buffer.
For consistency, POSIX.1‐2008 does not permit any of these behaviors.
Historically, vi did not always return the terminal to its original
modes; for example, ICRNL was modified if it was not originally set.
POSIX.1‐2008 does not permit this behavior.
Command Descriptions in vi
Motion commands are among the most complicated aspects of vi to
describe. With some exceptions, the text region and buffer type effect
of a motion command on a vi command are described on a case-by-case
basis. The descriptions of text regions in POSIX.1‐2008 are not
intended to imply direction; that is, an inclusive region from line n
to line n+5 is identical to a region from line n+5 to line n. This is
of more than academic interest—movements to marks can be in either
direction, and, if the wrapscan option is set, so can movements to
search points. Historically, lines are always stored into buffers in
text order; that is, from the start of the edit buffer to the end.
POSIX.1‐2008 requires conformance to historical practice.
Historically, command counts were applied to any associated motion, and
were multiplicative to any supplied motion count. For example, 2cw is
the same as c2w, and 2c3w is the same as c6w. POSIX.1‐2008 requires
this behavior. Historically, vi commands that used bigwords, words,
paragraphs, and sentences as objects treated groups of empty lines, or
lines that contained only <blank> characters, inconsistently. Some com‐
mands treated them as a single entity, while others treated each line
separately. For example, the w, W, and B commands treated groups of
empty lines as individual words; that is, the command would move the
cursor to each new empty line. The e and E commands treated groups of
empty lines as a single word; that is, the first use would move past
the group of lines. The b command would just beep at the user, or if
done from the start of the line as a motion command, fail in unexpected
ways. If the lines contained only (or ended with) <blank> characters,
the w and W commands would just beep at the user, the E and e commands
would treat the group as a single word, and the B and b commands would
treat the lines as individual words. For consistency and simplicity of
specification, POSIX.1‐2008 requires that all vi commands treat groups
of empty or blank lines as a single entity, and that movement through
lines ending with <blank> characters be consistent with other move‐
ments.
Historically, vi documentation indicated that any number of double-
quotes were skipped after punctuation marks at sentence boundaries;
however, implementations only skipped single-quotes. POSIX.1‐2008
requires both to be skipped.
Historically, the first and last characters in the edit buffer were
word boundaries. This historical practice is required by POSIX.1‐2008.
Historically, vi attempted to update the minimum number of columns on
the screen possible, which could lead to misleading information being
displayed. POSIX.1‐2008 makes no requirements other than that the cur‐
rent character being entered is displayed correctly, leaving all other
decisions in this area up to the implementation.
Historically, lines were arbitrarily folded between columns of any
characters that required multiple column positions on the screen, with
the exception of tabs, which terminated at the right-hand margin.
POSIX.1‐2008 permits the former and requires the latter. Implementa‐
tions that do not arbitrarily break lines between columns of characters
that occupy multiple column positions should not permit the cursor to
rest on a column that does not contain any part of a character.
The historical vi had a problem in that all movements were by buffer
lines, not by display or screen lines. This is often the right thing to
do; for example, single line movements, such as j or k, should work on
buffer lines. Commands like dj, or j., where . is a change command,
only make sense for buffer lines. It is not, however, the right thing
to do for screen motion or scrolling commands like <control>‐D, <con‐
trol>‐F, and H. If the window is fairly small, using buffer lines in
these cases can result in completely random motion; for example, 1<con‐
trol>‐D can result in a completely changed screen, without any overlap.
This is clearly not what the user wanted. The problem is even worse in
the case of the H, L, and M commands—as they position the cursor at the
first non-<blank> of the line, they may all refer to the same location
in large lines, and will result in no movement at all.
In addition, if the line is larger than the screen, using buffer lines
can make it impossible to display parts of the line—there are not any
commands that do not display the beginning of the line in historical
vi, and if both the beginning and end of the line cannot be on the
screen at the same time, the user suffers. Finally, the page and half-
page scrolling commands historically moved to the first non-<blank> in
the new line. If the line is approximately the same size as the screen,
this is inadequate because the cursor before and after a <control>‐D
command will refer to the same location on the screen.
Implementations of ex and vi exist that do not have these problems
because the relevant commands (<control>‐B, <control>‐D, <control>‐F,
<control>‐U, <control>‐Y, <control>‐E, H, L, and M) operate on display
(screen) lines, not (edit) buffer lines.
POSIX.1‐2008 does not permit this behavior by default because the stan‐
dard developers believed that users would find it too confusing. How‐
ever, historical practice has been relaxed. For example, ex and vi his‐
torically attempted, albeit sometimes unsuccessfully, to never put part
of a line on the last lines of a screen; for example, if a line would
not fit in its entirety, no part of the line was displayed, and the
screen lines corresponding to the line contained single '@' characters.
This behavior is permitted, but not required by POSIX.1‐2008, so that
it is possible for implementations to support long lines in small
screens more reasonably without changing the commands to be oriented to
the display (instead of oriented to the buffer). POSIX.1‐2008 also per‐
mits implementations to refuse to edit any edit buffer containing a
line that will not fit on the screen in its entirety.
The display area (for example, the value of the window edit option) has
historically been ``grown'', or expanded, to display new text when
local movements are done in displays where the number of lines dis‐
played is less than the maximum possible. Expansion has historically
been the first choice, when the target line is less than the maximum
possible expansion value away. Scrolling has historically been the next
choice, done when the target line is less than half a display away, and
otherwise, the screen was redrawn. There were exceptions, however, in
that ex commands generally always caused the screen to be redrawn.
POSIX.1‐2008 does not specify a standard behavior because there may be
external issues, such as connection speed, the number of characters
necessary to redraw as opposed to scroll, or terminal capabilities that
implementations will have to accommodate.
The current line in POSIX.1‐2008 maps one-to-one to a buffer line in
the file. The current column does not. There are two different column
values that are described by POSIX.1‐2008. The first is the current
column value as set by many of the vi commands. This value is remem‐
bered for the lifetime of the editor. The second column value is the
actual position on the screen where the cursor rests. The two are not
always the same. For example, when the cursor is backed by a multi-col‐
umn character, the actual cursor position on the screen has histori‐
cally been the last column of the character in command mode, and the
first column of the character in input mode.
Commands that set the current line, but that do not set the current
cursor value (for example, j and k) attempt to get as close as possible
to the remembered column position, so that the cursor tends to restrict
itself to a vertical column as the user moves around in the edit buf‐
fer. POSIX.1‐2008 requires conformance to historical practice, requir‐
ing that the display location of the cursor on the display line be
adjusted from the current column value as necessary to support this
historical behavior.
Historically, only a single line (and for some terminals, a single line
minus 1 column) of characters could be entered by the user for the
line-oriented commands; that is, :, !, /, or ?. POSIX.1‐2008 permits,
but does not require, this limitation.
Historically, ``soft'' errors in vi caused the terminal to be alerted,
but no error message was displayed. As a general rule, no error mes‐
sage was displayed for errors in command execution in vi, when the
error resulted from the user attempting an invalid or impossible
action, or when a searched-for object was not found. Examples of soft
errors included h at the left margin, <control>‐B or [[ at the begin‐
ning of the file, 2G at the end of the file, and so on. In addition,
errors such as %, ]], }, ), N, n, f, F, t, and T failing to find the
searched-for object were soft as well. Less consistently, / and ? dis‐
played an error message if the pattern was not found, /, ?, N, and n
displayed an error message if no previous regular expression had been
specified, and ; did not display an error message if no previous f, F,
t, or T command had occurred. Also, behavior in this area might reason‐
ably be based on a runtime evaluation of the speed of a network connec‐
tion. Finally, some implementations have provided error messages for
soft errors in order to assist naive users, based on the value of a
verbose edit option. POSIX.1‐2008 does not list specific errors for
which an error message shall be displayed. Implementations should con‐
form to historical practice in the absence of any strong reason to
diverge.
Page Backwards
The <control>‐B and <control>‐F commands historically considered it an
error to attempt to page past the beginning or end of the file, whereas
the <control>‐D and <control>‐U commands simply moved to the beginning
or end of the file. For consistency, POSIX.1‐2008 requires the latter
behavior for all four commands. All four commands still consider it an
error if the current line is at the beginning (<control>‐B, <con‐
trol>‐U) or end (<control>‐F, <control>‐D) of the file. Historically,
the <control>‐B and <control>‐F commands skip two lines in order to
include overlapping lines when a single command is entered. This makes
less sense in the presence of a count, as there will be, by definition,
no overlapping lines. The actual calculation used by historical imple‐
mentations of the vi editor for <control>‐B was:
((current first line) − count x (window edit option)) +2
and for <control>‐F was:
((current first line) + count x (window edit option)) −2
This calculation does not work well when intermixing commands with and
without counts; for example, 3<control>‐F is not equivalent to entering
the <control>‐F command three times, and is not reversible by entering
the <control>‐B command three times. For consistency with other vi com‐
mands that take counts, POSIX.1‐2008 requires a different calculation.
Scroll Forward
The 4BSD and System V implementations of vi differed on the initial
value used by the scroll command. 4BSD used:
((window edit option) +1) /2
while System V used the value of the scroll edit option. The System V
version is specified by POSIX.1‐2008 because the standard developers
believed that it was more intuitive and permitted the user a method of
setting the scroll value initially without also setting the number of
lines that are displayed.
Scroll Forward by Line
Historically, the <control>‐E and <control>‐Y commands considered it an
error if the last and first lines, respectively, were already on the
screen. POSIX.1‐2008 requires conformance to historical practice. His‐
torically, the <control>‐E and <control>‐Y commands had no effect in
open mode. For simplicity and consistency of specification,
POSIX.1‐2008 requires that they behave as usual, albeit with a single
line screen.
Clear and Redisplay
The historical <control>‐L command refreshed the screen exactly as it
was supposed to be currently displayed, replacing any '@' characters
for lines that had been deleted but not updated on the screen with
refreshed '@' characters. The intent of the <control>‐L command is to
refresh when the screen has been accidentally overwritten; for example,
by a write command from another user, or modem noise.
Redraw Screen
The historical <control>‐R command redisplayed only when necessary to
update lines that had been deleted but not updated on the screen and
that were flagged with '@' characters. There is no requirement that the
screen be in any way refreshed if no lines of this form are currently
displayed. POSIX.1‐2008 permits implementations to extend this command
to refresh lines on the screen flagged with '@' characters because they
are too long to be displayed in the current framework; however, the
current line and column need not be modified.
Search for tagstring
Historically, the first non-<blank> at or after the cursor was the
first character, and all subsequent characters that were word charac‐
ters, up to the end of the line, were included. For example, with the
cursor on the leading <space> or on the '#' character in the text
"#bar@", the tag was "#bar". On the character 'b' it was "bar", and on
the 'a' it was "ar". POSIX.1‐2008 requires this behavior.
Replace Text with Results from Shell Command
Historically, the <, >, and ! commands considered most cursor motions
other than line-oriented motions an error; for example, the command
>/foo<CR> succeeded, while the command >l failed, even though the text
region described by the two commands might be identical. For consis‐
tency, all three commands only consider entire lines and not partial
lines, and the region is defined as any line that contains a character
that was specified by the motion.
Move to Matching Character
Other matching characters have been left implementation-defined in
order to allow extensions such as matching '<' and '>' for searching
HTML, or #ifdef, #else, and #endif for searching C source.
Repeat Substitution
POSIX.1‐2008 requires that any c and g flags specified to the previous
substitute command be ignored; however, the r flag may still apply, if
supported by the implementation.
Return to Previous (Context or Section)
The [[, ]], (, ), {, and } commands are all affected by ``section
boundaries'', but in some historical implementations not all of the
commands recognize the same section boundaries. This is a bug, not a
feature, and a unique section-boundary algorithm was not described for
each command. One special case that is preserved is that the sentence
command moves to the end of the last line of the edit buffer while the
other commands go to the beginning, in order to preserve the tradi‐
tional character cut semantics of the sentence command. Historically,
vi section boundaries at the beginning and end of the edit buffer were
the first non-<blank> on the first and last lines of the edit buffer if
one exists; otherwise, the last character of the first and last lines
of the edit buffer if one exists. To increase consistency with other
section locations, this has been simplified by POSIX.1‐2008 to the
first character of the first and last lines of the edit buffer, or the
first and the last lines of the edit buffer if they are empty.
Sentence boundaries were problematic in the historical vi. They were
not only the boundaries as defined for the section and paragraph com‐
mands, but they were the first non-<blank> that occurred after those
boundaries, as well. Historically, the vi section commands were docu‐
mented as taking an optional window size as a count preceding the com‐
mand. This was not implemented in historical versions, so POSIX.1‐2008
requires that the count repeat the command, for consistency with other
vi commands.
Repeat
Historically, mapped commands other than text input commands could not
be repeated using the period command. POSIX.1‐2008 requires conformance
to historical practice.
The restrictions on the interpretation of special characters (for exam‐
ple, <control>‐H) in the repetition of text input mode commands is
intended to match historical practice. For example, given the input
sequence:
iab<control>-H<control>-H<control>-Hdef<escape>
the user should be informed of an error when the sequence is first
entered, but not during a command repetition. The character <control>‐T
is specifically exempted from this restriction. Historical implementa‐
tions of vi ignored <control>‐T characters that were input in the orig‐
inal command during command repetition. POSIX.1‐2008 prohibits this
behavior.
Find Regular Expression
Historically, commands did not affect the line searched to or from if
the motion command was a search (/, ?, N, n) and the final position was
the start/end of the line. There were some special cases and vi was not
consistent. POSIX.1‐2008 does not permit this behavior, for consis‐
tency. Historical implementations permitted but were unable to handle
searches as motion commands that wrapped (that is, due to the edit
option wrapscan) to the original location. POSIX.1‐2008 requires that
this behavior be treated as an error.
Historically, the syntax "/RE/0" was used to force the command to cut
text in line mode. POSIX.1‐2008 requires conformance to historical
practice.
Historically, in open mode, a z specified to a search command redis‐
played the current line instead of displaying the current screen with
the current line highlighted. For consistency and simplicity of speci‐
fication, POSIX.1‐2008 does not permit this behavior.
Historically, trailing z commands were permitted and ignored if entered
as part of a search used as a motion command. For consistency and sim‐
plicity of specification, POSIX.1‐2008 does not permit this behavior.
Execute an ex Command
Historically, vi implementations restricted the commands that could be
entered on the colon command line (for example, append and change), and
some other commands were known to cause them to fail catastrophically.
For consistency, POSIX.1‐2008 does not permit these restrictions. When
executing an ex command by entering :, it is not possible to enter a
<newline> as part of the command because it is considered the end of
the command. A different approach is to enter ex command mode by using
the vi Q command (and later resuming visual mode with the ex vi com‐
mand). In ex command mode, the single-line limitation does not exist.
So, for example, the following is valid:
Q
s/break here/break\
here/
vi
POSIX.1‐2008 requires that, if the ex command overwrites any part of
the screen that would be erased by a refresh, vi pauses for a character
from the user. Historically, this character could be any character; for
example, a character input by the user before the message appeared, or
even a mapped character. This is probably a bug, but implementations
that have tried to be more rigorous by requiring that the user enter a
specific character, or that the user enter a character after the mes‐
sage was displayed, have been forced by user indignation back into his‐
torical behavior. POSIX.1‐2008 requires conformance to historical prac‐
tice.
Shift Left (Right)
Refer to the Rationale for the ! and / commands. Historically, the <
and > commands sometimes moved the cursor to the first non-<blank> (for
example if the command was repeated or with _ as the motion command),
and sometimes left it unchanged. POSIX.1‐2008 does not permit this
inconsistency, requiring instead that the cursor always move to the
first non-<blank>. Historically, the < and > commands did not support
buffer arguments, although some implementations allow the specification
of an optional buffer. This behavior is neither required nor disallowed
by POSIX.1‐2008.
Execute
Historically, buffers could execute other buffers, and loops, infinite
and otherwise, were possible. POSIX.1‐2008 requires conformance to his‐
torical practice. The *buffer syntax of ex is not required in vi,
because it is not historical practice and has been used in some vi
implementations to support additional scripting languages.
Reverse Case
Historically, the ~ command ignored any associated count, and acted
only on the characters in the current line. For consistency with other
vi commands, POSIX.1‐2008 requires that an associated count act on the
next count characters, and that the command move to subsequent lines if
warranted by count, to make it possible to modify large pieces of text
in a reasonably efficient manner. There exist vi implementations that
optionally require an associated motion command for the ~ command.
Implementations supporting this functionality are encouraged to base it
on the tildedop edit option and handle the text regions and cursor
positioning identically to the yank command.
Append
Historically, counts specified to the A, a, I, and i commands repeated
the input of the first line count times, and did not repeat the subse‐
quent lines of the input text. POSIX.1‐2008 requires that the entire
text input be repeated count times.
Move Backward to Preceding Word
Historically, vi became confused if word commands were used as motion
commands in empty files. POSIX.1‐2008 requires that this be an error.
Historical implementations of vi had a large number of bugs in the word
movement commands, and they varied greatly in behavior in the presence
of empty lines, ``words'' made up of a single character, and lines con‐
taining only <blank> characters. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
Change to End-of-Line
Some historical implementations of the C command did not behave as
described by POSIX.1‐2008 when the $ key was remapped because they were
implemented by pushing the $ key onto the input queue and reprocessing
it. POSIX.1‐2008 does not permit this behavior. Historically, the C, S,
and s commands did not copy replaced text into the numeric buffers. For
consistency and simplicity of specification, POSIX.1‐2008 requires that
they behave like their respective c commands in all respects.
Delete
Historically, lines in open mode that were deleted were scrolled up,
and an @ glyph written over the beginning of the line. In the case of
terminals that are incapable of the necessary cursor motions, the edi‐
tor erased the deleted line from the screen. POSIX.1‐2008 requires con‐
formance to historical practice; that is, if the terminal cannot dis‐
play the '@' character, the line cannot remain on the screen.
Delete to End-of-Line
Some historical implementations of the D command did not behave as
described by POSIX.1‐2008 when the $ key was remapped because they were
implemented by pushing the $ key onto the input queue and reprocessing
it. POSIX.1‐2008 does not permit this behavior.
Join
An historical oddity of vi is that the commands J, 1J, and 2J are all
equivalent. POSIX.1‐2008 requires conformance to historical practice.
The vi J command is specified in terms of the ex join command with an
ex command count value. The address correction for a count that is past
the end of the edit buffer is necessary for historical compatibility
for both ex and vi.
Mark Position
Historical practice is that only lowercase letters, plus backquote and
single-quote, could be used to mark a cursor position. POSIX.1‐2008
requires conformance to historical practice, but encourages implementa‐
tions to support other characters as marks as well.
Repeat Regular Expression Find (Forward and Reverse)
Historically, the N and n commands could not be used as motion compo‐
nents for the c command. With the exception of the cN command, which
worked if the search crossed a line boundary, the text region would be
discarded, and the user would not be in text input mode. For consis‐
tency and simplicity of specification, POSIX.1‐2008 does not permit
this behavior.
Insert Empty Line (Below and Above)
Historically, counts to the O and o commands were used as the number of
physical lines to open, if the terminal was dumb and the slowopen
option was not set. This was intended to minimize traffic over slow
connections and repainting for dumb terminals. POSIX.1‐2008 does not
permit this behavior, requiring that a count to the open command behave
as for other text input commands. This change to historical practice
was made for consistency, and because a superset of the functionality
is provided by the slowopen edit option.
Put from Buffer (Following and Before)
Historically, counts to the p and P commands were ignored if the buffer
was a line mode buffer, but were (mostly) implemented as described in
POSIX.1‐2008 if the buffer was a character mode buffer. Because imple‐
mentations exist that do not have this limitation, and because pasting
lines multiple times is generally useful, POSIX.1‐2008 requires that
count be supported for all p and P commands.
Historical implementations of vi were widely known to have major prob‐
lems in the p and P commands, particularly when unusual regions of text
were copied into the edit buffer. The standard developers viewed these
as bugs, and they are not permitted for consistency and simplicity of
specification.
Historically, a P or p command (or an ex put command executed from open
or visual mode) executed in an empty file, left an empty line as the
first line of the file. For consistency and simplicity of specifica‐
tion, POSIX.1‐2008 does not permit this behavior.
Replace Character
Historically, the r command did not correctly handle the erase and word
erase characters as arguments, nor did it handle an associated count
greater than 1 with a <carriage-return> argument, for which it replaced
count characters with a single <newline>. POSIX.1‐2008 does not permit
these inconsistencies.
Historically, the r command permitted the <control>‐V escaping of
entered characters, such as <ESC> and the <carriage-return>; however,
it required two leading <control>‐V characters instead of one.
POSIX.1‐2008 requires that this be changed for consistency with the
other text input commands of vi.
Historically, it is an error to enter the r command if there are less
than count characters at or after the cursor in the line. While a rea‐
sonable and unambiguous extension would be to permit the r command on
empty lines, it would require that too large a count be adjusted to
match the number of characters at or after the cursor for consistency,
which is sufficiently different from historical practice to be avoided.
POSIX.1‐2008 requires conformance to historical practice.
Replace Characters
Historically, if there were autoindent characters in the line on which
the R command was run, and autoindent was set, the first <newline>
would be properly indented and no characters would be replaced by the
<newline>. Each additional <newline> would replace n characters, where
n was the number of characters that were needed to indent the rest of
the line to the proper indentation level. This behavior is a bug and is
not permitted by POSIX.1‐2008.
Undo
Historical practice for cursor positioning after undoing commands was
mixed. In most cases, when undoing commands that affected a single
line, the cursor was moved to the start of added or changed text, or
immediately after deleted text. However, if the user had moved from the
line being changed, the column was either set to the first non-<blank>,
returned to the origin of the command, or remained unchanged. When
undoing commands that affected multiple lines or entire lines, the cur‐
sor was moved to the first character in the first line restored. As an
example of how inconsistent this was, a search, followed by an o text
input command, followed by an undo would return the cursor to the loca‐
tion where the o command was entered, but a cw command followed by an o
command followed by an undo would return the cursor to the first
non-<blank> of the line. POSIX.1‐2008 requires the most useful of these
behaviors, and discards the least useful, in the interest of consis‐
tency and simplicity of specification.
Yank
Historically, the yank command did not move to the end of the motion if
the motion was in the forward direction. It moved to the end of the
motion if the motion was in the backward direction, except for the _
command, or for the G and ' commands when the end of the motion was on
the current line. This was further complicated by the fact that for a
number of motion commands, the yank command moved the cursor but did
not update the screen; for example, a subsequent command would move the
cursor from the end of the motion, even though the cursor on the screen
had not reflected the cursor movement for the yank command.
POSIX.1‐2008 requires that all yank commands associated with backward
motions move the cursor to the end of the motion for consistency, and
specifically, to make ' commands as motions consistent with search pat‐
terns as motions.
Yank Current Line
Some historical implementations of the Y command did not behave as
described by POSIX.1‐2008 when the '_' key was remapped because they
were implemented by pushing the '_' key onto the input queue and repro‐
cessing it. POSIX.1‐2008 does not permit this behavior.
Redraw Window
Historically, the z command always redrew the screen. This is permitted
but not required by POSIX.1‐2008, because of the frequent use of the z
command in macros such as map n nz. for screen positioning, instead of
its use to change the screen size. The standard developers believed
that expanding or scrolling the screen offered a better interface for
users. The ability to redraw the screen is preserved if the optional
new window size is specified, and in the <control>‐L and <control>‐R
commands.
The semantics of z^ are confusing at best. Historical practice is that
the screen before the screen that ended with the specified line is dis‐
played. POSIX.1‐2008 requires conformance to historical practice.
Historically, the z command would not display a partial line at the top
or bottom of the screen. If the partial line would normally have been
displayed at the bottom of the screen, the command worked, but the par‐
tial line was replaced with '@' characters. If the partial line would
normally have been displayed at the top of the screen, the command
would fail. For consistency and simplicity of specification,
POSIX.1‐2008 does not permit this behavior.
Historically, the z command with a line specification of 1 ignored the
command. For consistency and simplicity of specification, POSIX.1‐2008
does not permit this behavior.
Historically, the z command did not set the cursor column to the first
non-<blank> for the character if the first screen was to be displayed,
and was already displayed. For consistency and simplicity of specifica‐
tion, POSIX.1‐2008 does not permit this behavior.
Input Mode Commands in vi
Historical implementations of vi did not permit the user to erase more
than a single line of input, or to use normal erase characters such as
line erase, worderase, and erase to erase autoindent characters. As
there exist implementations of vi that do not have these limitations,
both behaviors are permitted, but only historical practice is required.
In the case of these extensions, vi is required to pause at the autoin‐
dent and previous line boundaries.
Historical implementations of vi updated only the portion of the screen
where the current cursor character was displayed. For example, consider
the vi input keystrokes:
iabcd<escape>0C<tab>
Historically, the <tab> would overwrite the characters "abcd" when it
was displayed. Other implementations replace only the 'a' character
with the <tab>, and then push the rest of the characters ahead of the
cursor. Both implementations have problems. The historical implementa‐
tion is probably visually nicer for the above example; however, for the
keystrokes:
iabcd<ESC>0R<tab><ESC>
the historical implementation results in the string "bcd" disappearing
and then magically reappearing when the <ESC> character is entered.
POSIX.1‐2008 requires the former behavior when overwriting erase-col‐
umns—that is, overwriting characters that are no longer logically part
of the edit buffer—and the latter behavior otherwise.
Historical implementations of vi discarded the <control>‐D and <con‐
trol>‐T characters when they were entered at places where their command
functionality was not appropriate. POSIX.1‐2008 requires that the <con‐
trol>‐T functionality always be available, and that <control>‐D be
treated as any other key when not operating on autoindent characters.
NUL
Some historical implementations of vi limited the number of characters
entered using the NUL input character to 256 bytes. POSIX.1‐2008 per‐
mits this limitation; however, implementations are encouraged to remove
this limit.
<control>‐D
See also Rationale for the input mode command <newline>. The hidden
assumptions in the <control>‐D command (and in the vi autoindent speci‐
fication in general) is that <space> characters take up a single column
on the screen and that <tab> characters are comprised of an integral
number of <space> characters.
<newline>
Implementations are permitted to rewrite autoindent characters in the
line when <newline>, <carriage-return>, <control>‐D, and <control>‐T
are entered, or when the shift commands are used, because historical
implementations have both done so and found it necessary to do so. For
example, a <control>‐D when the cursor is preceded by a single <tab>,
with tabstop set to 8, and shiftwidth set to 3, will result in the
<tab> being replaced by several <space> characters.
<control>‐T
See also the Rationale for the input mode command <newline>. Histori‐
cally, <control>‐T only worked if no non-<blank> characters had yet
been input in the current input line. In addition, the characters
inserted by <control>‐T were treated as autoindent characters, and
could not be erased using normal user erase characters. Because imple‐
mentations exist that do not have these limitations, and as moving to a
column boundary is generally useful, POSIX.1‐2008 requires that both
limitations be removed.
<control>‐V
Historically, vi used ^V, regardless of the value of the literal-next
character of the terminal. POSIX.1‐2008 requires conformance to his‐
torical practice.
The uses described for <control>‐V can also be accomplished with <con‐
trol>‐Q, which is useful on terminals that use <control>‐V for the
down-arrow function. However, most historical implementations use <con‐
trol>‐Q for the termios START character, so the editor will generally
not receive the <control>‐Q unless stty ixon mode is set to off. (In
addition, some historical implementations of vi explicitly set ixon
mode to on, so it was difficult for the user to set it to off.) Any of
the command characters described in POSIX.1‐2008 can be made ineffec‐
tive by their selection as termios control characters, using the stty
utility or other methods described in the System Interfaces volume of
POSIX.1‐2008.
<ESC>
Historically, SIGINT alerted the terminal when used to end input mode.
This behavior is permitted, but not required, by POSIX.1‐2008.
FUTURE DIRECTIONS
None.
SEE ALSO
ed, ex, stty
The Base Definitions volume of POSIX.1‐2008, Section 12.2, Utility Syn‐
tax Guidelines
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 VI(1P)
