Manual Pages  — RE_COMP

The re_comp() function compiles a string into an internal form suitable for pattern matching. The re_exec() function checks the argument string against the last string passed to re_comp().

The re_comp() function 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.

The re_exec() function 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 NULs. The regular expressions recognized are described in the manual entry for ed(1), given the above difference.

The re_comp() function returns "no previous regular expression" or one of the strings generated by regerror(3).