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OpenDarwin 7.2.1 - man page for regsub (opendarwin section n)

regsub(n)			      Tcl Built-In Commands				regsub(n)

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NAME
       regsub - Perform substitutions based on regular expression pattern matching

SYNOPSIS
       regsub ?switches? exp string subSpec ?varName?						  |
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DESCRIPTION
       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 sub-
       Spec.  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 backslashes may be used
       in subSpec to prevent special interpretation of ``&'' or ``\0'' or  ``\n''  or  backslash.
       The  use  of  backslashes  in subSpec 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  back-
       slashes.

       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 substitution is performed  for
		 each  of  these  ranges.   Without  this switch only the first matching range is
		 found and substituted.  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 meaning.  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) embed-
		      ded 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 manual page).

       -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 string.

       -start index
		 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 man-
       ual entry for regexp for details on the interpretation of regular expressions.

SEE ALSO
       regexp(n), re_syntax(n)

KEYWORDS
       match, pattern, regular expression, substitute

Tcl					       8.3					regsub(n)


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