Is it possible to repeat getopt

Question

I am trying to create a basic shell with built-in commands and I am having some problems with getopt. Here is the result (using valgrind):

$ mkdir -p foo/bar mkdir -p foo/bar FLAGON $ mkdir -p foo/test mkdir -p foo/test ==15377== Invalid read of size 1 ==15377== at 0x5201BBE: _getopt_internal_r (in /usr/lib/libc-2.17.so) ==15377== by 0x5202CEA: _getopt_internal (in /usr/lib/libc-2.17.so) ==15377== by 0x5202D37: getopt (in /usr/lib/libc-2.17.so) ==15377== by 0x40351A: shell_ns_cmd_mkdir (shell.c:542) ==15377== by 0x403AB4: normal_shell_cb (shell.c:610) ==15377== by 0x402E8E: shell_mainloop (shell.c:402) ==15377== by 0x401B67: main (main.c:52) ==15377== Address 0x54e0912 is 2 bytes inside a block of size 3 free'd ==15377== at 0x4C2AD3C: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) ==15377== by 0x402C93: shell_mainloop (shell.c:384) ==15377== by 0x401B67: main (main.c:52) ==15377== $ 

And here is the source (cropped):

 for (i = 0; i < argc; i++) { puts(argv[i]); } while ((c = getopt(argc, argv, "p")) != -1) { switch (c) { case 'p': puts("FLAGON"); mkparents = true; break; case '?': fprintf(stderr, "invalid option -- %c", optopt); ret = 127; goto end; break; } } 

Therefore, at the first start ( mkdir -p ) it recognizes ( -p ), and the second time it does not work. Any ideas?

Answer 1

If you want to scan multiple vectors, you need to reset getopt by setting optind to 1.

The optind variable is the index of the next element argv [] the vector to be processed. It must be initialized by 1 system , and getopt () must update it when it finishes with each element of ARGV [].

If setting optind to 1 does not work, try 0 , I think I remember reading about it somewhere.