explain_getpgrp_or_die - get process group and report errors

       libexplain version 1.4
       Copyright (C) 2011 Peter Miller

                                                                                       explain_getpgrp_or_die(3)

       The explain_getpgrp_or_die function is used to call the getpgrp(2) system call. On failure an explanation
       will be printed to stderr, obtained from the explain_getpgrp(3) function, and then the process terminates
       by calling exit(EXIT_FAILURE).

       The  explain_getpgrp_on_error  function  is  used  to  call  the  getpgrp(2)  system  call. On failure an
       explanation will be printed to stderr, obtained from the explain_getpgrp(3) function, but  still  returns
       to the caller.

       pid     The pid, exactly as to be passed to the getpgrp(2) system call.

   APIInconsistenciesNote:  the  getpgrp(2) function has two implementations.  The POSIX.1 version has no arguments, while the
       BSD version has one argument.  For simplicity of implementation, the argument list seen here includes the
       pid argument.

       The POSIX.1 getpgid() semanatics can be obtained by calling getpgrp(0) on BSD systems, and  this  is  the
       API for libexplain, even on systems that do not use the BSD API.

       The explain_getpgrp_or_die function is intended to be used in a fashion similar to the following example:
              pid_t result = explain_getpgrp_or_die(pid);

       explain_getpgrp_or_die - get process group and report errors

       The  explain_getpgrp_or_die  function  only  returns  on success, see getpgrp(2) for more information. On
       failure, prints an explanation and exits, it does not return.

       The explain_getpgrp_on_error function always returns the value return by the  wrapped  getpgrp(2)  system
       call.

getpgrp(2)
               get process group

       explain_getpgrp(3)
               explain getpgrp(2) errors

       exit(2) terminate the calling process

       #include <libexplain/getpgrp.h>
       pid_t explain_getpgrp_or_die(pid_t pid);
       pid_t explain_getpgrp_on_error(pid_t pid);