Question on Regular Expression

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LEARN ABOUT BSD

re_comp

REGEX(3)						     Library Functions Manual							  REGEX(3)

NAME

       re_comp, re_exec - regular expression handler

SYNOPSIS

       char *re_comp(s)
       char *s;

       re_exec(s)
       char *s;

DESCRIPTION

       Re_comp	compiles a string into an internal form suitable for pattern matching.	Re_exec checks the argument string against the last string
       passed to re_comp.

       Re_comp returns 0 if the string s was compiled successfully; otherwise a string containing an error message  is	returned.  If  re_comp	is
       passed 0 or a null string, it returns without changing the currently compiled regular expression.

       Re_exec returns 1 if the string s matches the last compiled regular expression, 0 if the string s failed to match the last compiled regular
       expression, and -1 if the compiled regular expression was invalid (indicating an internal error).

       The strings passed to both re_comp and re_exec may have trailing or embedded newline characters; they are terminated by nulls.  The regular
       expressions recognized are described in the manual entry for ed(1), given the above difference.

SEE ALSO

       ed(1), ex(1), egrep(1), fgrep(1), grep(1)

DIAGNOSTICS

       Re_exec returns -1 for an internal error.

       Re_comp returns one of the following strings if an error occurs:

	    No previous regular expression,
	    Regular expression too long,
	    unmatched (,
	    missing ],
	    too many () pairs,
	    unmatched ).

3rd Berkeley Distribution					   May 15, 1985 							  REGEX(3)

UNIX for Dummies Questions & Answers