Manual Pages for UNIX Darwin command on man regsub

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

NAME

regsub - Perform substitutions based on regular expression pattern

matching

SYNOPSIS

rreeggssuubb ?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 rreessyynnttaaxx 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 rreeggssuubb start with - then they are treated

as switches. The following switches are currently supported:

-aallll 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 -aallll is specified, then ``&'' and ``\n'' sequences

are handled for each substitution using the information from the corresponding match.

-eexxppaannddeedd Enables use of the expanded regular expression syntax

where whitespace and comments are ignored. This is the same as specifying the ((??xx)) embedded option (see the rreessyynnttaaxx manual page).

-lliinnee 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 -lliinneessttoopp and -lliinneeaanncchhoorr, or the ((??nn))

embedded option (see the rreessyynnttaaxx manual page).

-lliinneessttoopp Changes the behavior of `[^' bracket expressions and `.'

so that they stop at newlines. This is the same as specifying the ((??pp)) embedded option (see the rreessyynnttaaxx manual page).

-lliinneeaanncchhoorr 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 ((??ww)) embedded option (see the rreessyynnttaaxx manual page).

-nnooccaassee 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.

-ssttaarrtt 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 rreeggeexxpp for details on the interpretation of regular expressions.