GETPGRP(2) System Calls GETPGRP(2)
getpgrp - get process group
pid_t _getpgrp (pid_t pid);
pid_t getpgrp (void);
getpgrp returns the process group of the current process. _getpgrp
returns the process group of the process specified by pid.
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 foreground and may read, while others
will block with a signal if they attempt to read.
This call is thus used by programs such as csh(1) to create process
groups in implementing job control. The tcgetpgrp and tcsetpgrp calls
are used to get/set the process group of the control terminal.
On success, the requested process group is returned. On failure, -1 is
returned and errno is set.
The getpgrp function conforms to IEEE Std 1003.1-1988 (POSIX).
This version of getpgrp differs from past GNO (pre-v2.0.6) and Berkeley
versions by not taking a pid_t pid argument. This incompatibility is
required by POSIX 1003.1-88.
From the POSIX 1003.1-88 Rationale:
4.3BSD provides a getpgrp function that returns the process
group ID for a specified process. Although this function is
used to support job control, all known job-control shells always
specify the calling process with this function. Thus, the sim-
pler System V getpgrp suffices, and the added complexity of the
4.3BSD getpgrp has been omitted from POSIX.1.
The older version of getpgrp which takes an argument is available as
the non-standard function _getpgrp.
job_control(2), setpgid(2), termios(4)
The getpgrp function call appeared in 4.0BSD.
GNO 16 January 1997 GETPGRP(2)
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