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 returned by
() returns the process group of the
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 system call is thus used by programs such as
to create process groups in implementing
job control. The
() calls are used to get/set the
process group of the control terminal.
() system call always succeeds.
Upon successful completion, the
system call returns the process group of the specified process; otherwise, it
returns a value of -1 and sets errno
indicate the error.
This version of
() differs from past
Berkeley versions by not taking a pid_t pid
argument. This incompatibility is required by IEEE
Std 1003.1-1990 (“POSIX.1”)
From the IEEE Std 1003.1-1990
() system call 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
suffices, and the added complexity of the 4.3BSD
() has been omitted from POSIX.1.
The old functionality is available from the
() system call.
() system call will succeed
- there is no process whose process ID equals
() system call is expected to
conform to IEEE Std 1003.1-1990
() system call appeared in
() system call is derived from its
usage in AT&T System V Release 4