text: setsid - creates a session and sets the process group ID
  Synopsis
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  #include <unistd.h>
  pid_t setsid(void);.
  On success, the (new) session ID of the calling process is returned. On error, (pid_t) -1 is returned, and errno is set to indicate the error.
  SVr4, POSIX.1-2001.
  A child created via fork(2) inherits its parents session ID. The session ID is preserved across an execve(2).
  A process group leader is a process with process group ID equal to its PID. In order to be sure that setsid() will succeed, fork(2) and _exit(2), and have the child do setsid().
  getsid(2), setpgid(2), setpgrp(2), tcgetsid(3), credentials(7)
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