NAME
getpgrp,
getpgid —
get process group
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
pid_t
getpgrp(
void);
pid_t
getpgid(
pid_t
pid);
DESCRIPTION
The process group of the current process is returned by
getpgrp(). The process group of the
pid process is returned by
getpgid().
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.
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() 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 System V
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() function.
ERRORS
getpgrp() always succeeds, however
getpgid()
will succeed unless:
-
-
- [
ESRCH
]
- if there is no process with a process ID equal to
pid.
SEE ALSO
setpgid(2),
termios(4)
STANDARDS
The
getpgrp() function conforms to
IEEE Std
1003.1-1988 (“POSIX.1”).
HISTORY
The
getpgrp() function call appeared in
4.0BSD. The
getpgid() function call
is derived from its usage in
AT&T System V
Release 4 UNIX, and first appeared in
NetBSD
1.3.