getpgrp(2)getpgrp(2)Namegetpgrp - get process group
pgrp = getpgrp(pid)
The system call returns the process group of the specified process. If
pid is zero, the call applies to the current process.
Process groups are used for distribution of signals and by terminals to
arbitrate requests for their input. Processes that have the same
process group as the terminal are the foreground and may read, while
others block with a signal if they attempt to read.
This call is used by programs such as to create process groups in
implementing job control. The TIOCGPGRP and TIOCSPGRP calls described
in are used to get and set the process group of the control terminal.
When your program is compiled in the System V or POSIX environment, is
called without arguments and the process group of the current process
Additionally, in POSIX mode, returns a value type of pid_t.
The call fails under the following condition:
[ESRCH] No such process, PID.
See Alsogetuid(2), setpgrp(2), tty(4)getpgrp(2)