vis(1)vis(1)NAME
vis, inv - make unprintable and non-ASCII characters in a file visible
or invisible
SYNOPSIS
file ...
file ...
DESCRIPTION
reads characters from each file in sequence and writes them to the
standard output, converting those that are not printable or not ASCII
into a visible form. inv performs the inverse function, reading print‐
able characters from each file, returning them to non-printable or non-
ASCII form, if appropriate, then writing them to standard output;
Non-printable ASCII characters are represented using C-like escape con‐
ventions:
backslash
backspace
escape
form-feed
new-line
carriage return
space
horizontal tab
vertical tab
the character whose
ASCII code is the 3-digit octal number n.
the character whose
ASCII code is the 2-digit hexadecimal number n.
Non-ASCII single- or multi-byte characters are examined one byte at a
time. For each byte, if it can be displayed as an ASCII character, it
is treated as if it is an ASCII character; Otherwise, it is represented
in the following conventions:
the 8-bit character whose
code value is the 3-digit octal number n.
the 8-bit character whose
code value is the 2-digit hexadecimal number n.
Space, horizontal-tab, and new-line characters can be treated as print‐
able (and therefore passed unaltered to the output) or non-printable
depending on the options selected. Backslash, although printable, is
expanded by vis, to a pair of backslashes so that when they are passed
back through inv, they convert back to a single backslash.
If no input file is given, or if the argument is encountered, and inv
read from the standard input.
Options
and recognize the following options:
Treat new-line, space, and horizontal tab as non-printable char‐
acters.
expands them visibly as and rather than passing them
directly to the output. discards these characters,
expecting only the printable expansions. New-line char‐
acters are inserted by every 16 bytes so that the output
will be in a form that is usable by most editors.
Make and silent about non-existent files, identical input and
output, and write errors. Normally, no input file can
be the same as the output file unless it is a special
file.
Treat horizontal-tab and space characters as non-printable
in the same manner that treats them.
Cause output to be unbuffered (byte-by-byte);
normally, output is buffered.
Cause output to be in hexadecimal form rather than the default
octal form. Either form is accepted to as input.
EXTERNAL INFLUENCES
Environment Variables
determines the language in which messages are displayed.
International Code Set Support
Single- and multi-byte character code sets are supported.
WARNINGS
Redirecting output to an input file destroys the original data. There‐
fore, command forms such as
should be avoided unless the source file can be safely discarded.
AUTHOR
was developed by HP.
SEE ALSOcat(1), echo(1), od(1).
vis(1)
