re_comp, re_exec - BSD regex functions
char *re_comp(char *regex));
int re_exec(char *string));
re_comp is used to compile the null-terminated regular
expression pointed to by regex. The compiled pattern occu-
pies a static area, the pattern buffer, which is overwritten
by subsequent use of re_comp. If regex is NULL, no opera-
tion is performed and the pattern buffer's contents are not
re_exec is used to assess whether the null-terminated string
pointed to by string matches the previously compiled regex.
re_comp returns NULL on successful compilation of regex oth-
erwise it returns a pointer to an appropriate error message.
re_exec returns 1 for a successful match, zero for failure.
regex(7), GNU regex manual