getopt(3) On mac os and CentOS
c, centos, getopt, macos
Solution
The documented behaviour of GNU `getopt()` is to stop at the first non-option argument only when in POSIX mode, which can be set via a `+` at the start of the option string or by setting the `POSIXLY_CORRECT` environment variable.
In its default mode, GNU `getopt()` 'permutes the contents of `argv` as it scans, so eventually all the non-options are at the end.'
You are hitting this difference in the behaviour — it is the difference between GNU `getopt()` and BSD `getopt()` behaviour, because the BSD `getopt()` has POSIX semantics.
Problem
I compile the same code by gcc on OSX and CentOS: ``` while (( opt = getopt (argc, argv, "hp:" )) != -1 ) { fprintf (stderr,"+++++++++++ %d\n\n", opt ); switch ( opt ) { case 'h': fprintf(stderr, "Help Page \n %s", help_str); return 1; case 'p': filename = optarg ; fprintf(stderr,"================== %s\n",optarg); break; case '?': printf("ZHZHZHZHZHUT\n"); return 3; default: break; } } ``` Then I try to run `./a.out -p ./file.txt ya.ru` and `./a.out ya.ru -p ./file.txt` On CentOS 6.5 both variants work. But on MAC OS X(10.9) variant `./a.out ya.ru -p ./file.txt` (free parameter before dependent parameter ) does not work. `-p` and `/file.txt` are used as simple arguments (not by `getopt`). Full code is here Thanks.