regsub man page on CentOS

Man page or keyword search:  
man Server   8420 pages
apropos Keyword Search (all sections)
Output format
CentOS logo
[printable version]

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

______________________________________________________________________________

NAME
       regsub  -  Perform  substitutions  based	 on regular expression pattern
       matching

SYNOPSIS
       regsub ?switches? exp string subSpec ?varName?			       │
_________________________________________________________________

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 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
       backslashes.

       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
		      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 manual  entry  for  regexp  for
       details on the interpretation of regular expressions.

EXAMPLES
       Replace	(in the string in variable string) every instance of foo which
       is a word by itself with bar:
	      regsub -all {\<foo\>} $string bar string

       Insert double-quotes around the first instance of the word interesting,
       however it is capitalised.
	      regsub -nocase {\<interesting\>} $string {"&"} string

       Convert	all  non-ASCII	and  Tcl-significant characters into \u escape
       sequences by using regsub and subst in combination:
	      # This RE is just a character class for everything "bad"
	      set RE {[][{}\$\s\u0100-\uffff]}

	      # We will substitute with a fragment of Tcl script in brackets
	      set substitution {[format \\\\u%04x [scan "\\&" %c]]}

	      # Now we apply the substitution to get a subst-string that
	      # will perform the computational parts of the conversion.
	      set quoted [subst [regsub -all $RE $string $substitution]]

SEE ALSO
       regexp(n), re_syntax(n), subst(n)

KEYWORDS
       match, pattern, regular expression, substitute

Tcl				      8.3			     regsub(n)
[top]

List of man pages available for CentOS

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net