term% cat index.txt REGEXP(3) Library Functions Manual REGEXP(3)
NAME
regcomp, regexec, regsub, regerror - regular expression handler
SYNOPSIS
#include <regexp.h>
regexp *regcomp(exp)
char *exp;
int regexec(prog, string)
struct regexp *prog;
char *string;
regsub(prog, source, dest)
struct regexp *prog;
char *source;
char *dest;
regerror(msg)
char *msg;
DESCRIPTION
Regcomp compiles an egrep(1)-styleregularexpressionandreturns a pointer
to an object with the following structure. The object is allocated by
malloc(2) and may be released by free.
/* Copyright (C) 1996-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _REGEXP_H
#define _REGEXP_H 1
/* The contents of this header file were originally standardized in
the Single Unix Specification, Issue 3 (1992). In Issue 4 (1994)
the header was marked as TO BE WITHDRAWN, and new applications
were encouraged to use <regex.h> instead. It was officially
withdrawn from the standard in Issue 6 (aka POSIX.1-2001).
The GNU C Library provided this header through version 2.22. */
#error "The GNU C Library no longer implements <regexp.h>."
#error "Please update your code to use <regex.h> instead (no trailing 'p')."
#endif /* regexp.h */
Startp[n] points to the first character of the substring of string that
matches the nth parenthesized subexpression (the subexpression intro‐
duced by the nth left parenthesis). Endp[n] points to the first char‐
acter following that substring. The character array program contains
the compiled form of the regular expression.
Regexec matches a null-terminated string against the compiled regular
expression in prog. If it matches, regexec returns a non-zero value
and fills in the startp and endp fields to describe the match, in which
`*', `+', and `?' matches are extended as far as possible. By conven‐
tion, startp[0] and endp[0] refer to the substring that matches the
complete regular expression.
Regsub places in dest a substitution instance of source in the context
of the last regexec performed using prog. Each instance of `\n', where
n is a digit, is replaced by the string delimited by startp[n] and
endp[n]. Each instance of `&' is replaced by the string delimited by
startp [0] and endp [0]. The result is placed in the area pointed to
by dest .
Regerror, called whenever an error is detected in regcomp, regexec, or
regsub, writes the string msg on the standard error file and exits.
Regerror can be replaced to perform special error processing.
DIAGNOSTICS
Regcomp returns 0 for an illegal expression or other failure. Regexec
returns 0 if string is not accepted.
SEE ALSO
egrep(1), expr(1)
REGEXP(3)