strsep - extract token from string
char *strsep(char **stringp, const char *delim);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
If *stringp is NULL, the strsep() function returns NULL and does nothing else. Otherwise, this function finds the first token in the string
*stringp, where tokens are delimited by symbols in the string delim. This token is terminated with a '\0' character (by overwriting the delimiter)
and *stringp is updated to point past the token. In case no delimiter was found, the token is taken to be the entire string *stringp, and *stringp
is made NULL.
The strsep() function returns a pointer to the token, that is, it returns the original value of *stringp.
The strsep() function was introduced as a replacement for strtok(3), since the latter cannot handle empty fields. However, strtok(3) conforms to
C89/C99 and hence is more portable.