|GETPGRP(2)||System Calls Manual||GETPGRP(2)|
— get process group
Standard C Library (libc, -lc)
The process group of the current process is returned by
The process group of the process identified by pid is
If pid is zero,
returns the process group of 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 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
calls are used to get/set the process group of the control terminal.
getpgrp() call always succeeds. Upon
successful completion, the
getpgid() call returns
the process group of the specified process; otherwise, it returns a value of
-1 and sets errno to indicate the error.
getpgid() will succeed unless:
getpgrp() function call appeared in
function call is derived from its usage in System V Release 4.
getpgrp() function call is expected to
conform to IEEE Std 1003.1-1990
This version of
getpgrp() differs from
past Berkeley versions by not taking a pid_t pid
argument. This incompatibility is required by IEEE Std
From the IEEE Std 1003.1-1990 (“POSIX.1”) 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 simpler AT&T
System V UNIX
getpgrp() suffices, and
the added complexity of the 4.3BSD
getpgrp() has been omitted from POSIX.1. The old
functionality is available from the
|June 4, 1993||macOS 14.1|