regsub(n) Tcl Built-In Commands regsub(n)______________________________________________________________________________NAMEregsub - Perform substitutions based on regular expression pattern
SYNOPSISregsub ?switches? exp string subSpec ?varName? │
This command matches the regular expression exp against string, and │
either copies string to the variable whose name is given by varName or │
returns string if varName is not present. (Regular expression matching
is described in the re_syntax reference page.) If there is a match,
then while copying string to varName (or to the result of this command │
if varName is not present) the portion of string that matched exp is
replaced with subSpec. If subSpec contains a ``&'' or ``\0'', then it
is replaced in the substitution with the portion of string that matched
exp. If subSpec contains a ``\n'', where n is a digit between 1 and 9,
then it is replaced in the substitution with the portion of string that
matched the n-th parenthesized subexpression of exp. Additional back‐
slashes may be used in subSpec to prevent special interpretation of
``&'' or ``\0'' or ``\n'' or backslash. The use of backslashes in sub‐
Spec tends to interact badly with the Tcl parser's use of backslashes,
so it's generally safest to enclose subSpec in braces if it includes
If the initial arguments to regsub start with - then they are treated
as switches. The following switches are currently supported:
-all All ranges in string that match exp are found and substitu‐
tion is performed for each of these ranges. Without this
switch only the first matching range is found and substi‐
tuted. If -all is specified, then ``&'' and ``\n'' sequences
are handled for each substitution using the information from
the corresponding match.
-expanded Enables use of the expanded regular expression syntax
where whitespace and comments are ignored. This is the
same as specifying the (?x) embedded option (see the
re_syntax manual page).
-line Enables newline-sensitive matching. By default, newline
is a completely ordinary character with no special mean‐
ing. With this flag, `[^' bracket expressions and `.'
never match newline, `^' matches an empty string after
any newline in addition to its normal function, and `$'
matches an empty string before any newline in addition
to its normal function. This flag is equivalent to
specifying both -linestop and -lineanchor, or the (?n)
embedded option (see the re_syntax manual page).
-linestop Changes the behavior of `[^' bracket expressions and `.'
so that they stop at newlines. This is the same as
specifying the (?p) embedded option (see the re_syntax
-lineanchor Changes the behavior of `^' and `$' (the ``anchors'') so
they match the beginning and end of a line respectively.
This is the same as specifying the (?w) embedded option
(see the re_syntax manual page).
-nocase Upper-case characters in string will be converted to lower-
case before matching against exp; however, substitutions
specified by subSpec use the original unconverted form of
Specifies a character index offset into the string to start
matching the regular expression at. When using this switch,
`^' will not match the beginning of the line, and \A will
still match the start of the string at index. index will be
constrained to the bounds of the input string.
-- Marks the end of switches. The argument following this one
will be treated as exp even if it starts with a -.
If varName is supplied, the command returns a count of the number of │
matching ranges that were found and replaced, otherwise the string │
after replacement is returned. See the manual entry for regexp for
details on the interpretation of regular expressions.
SEE ALSOregexp(n), re_syntax(n)KEYWORDS
match, pattern, regular expression, substitute
Tcl 8.3 regsub(n)