|GETPGRP(2)||System Calls Manual||GETPGRP(2)|
LIBRARY¶Standard C Library (libc, -lc)
DESCRIPTION¶The process group of the current process is returned by
getpgrp(). The process group of the process identified by pid is returned by
getpgid(). If pid is zero,
getpgid() 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 system call is thus used by programs such as
csh(1) to create process groups in implementing job
tcsetpgrp() calls are used to get/set the process
group of the control terminal.
getpgrp() system call always succeeds. Upon successful completion, the
getpgid() system call returns the process group of the specified process; otherwise, it returns a value of -1 and sets errno to indicate the error.
COMPATIBILITY¶This version of
getpgrp() 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 (“POSIX.1”) Rationale:
4.3BSD provides a
getpgrp() 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
getpgrp() suffices, and
the added complexity of the 4.3BSD
getpgrp() has been omitted from POSIX.1. The old
functionality is available from the
getpgid() system call will succeed unless:
- there is no process whose process ID equals pid
SEE ALSO¶getsid(2), setpgid(2), termios(4)
getpgrp() system call is expected to conform to IEEE Std 1003.1-1990 (“POSIX.1”).
getpgrp() system call appeared in 4.0BSD. The
getpgid() system call is derived from its usage in AT&T System V Release 4 UNIX.
|June 4, 1993||Linux 4.9.0-9-amd64|