GETPGRP(2) | System Calls Manual | GETPGRP(2) |
getpgrp
, getpgid
—
#include <unistd.h>
pid_t
getpgrp
(void);
pid_t
getpgid
(pid_t
pid);
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.
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.
getpgrp
() always succeeds, however
getpgid
() will succeed unless:
ESRCH
]getpgrp
() function conforms to IEEE
Std 1003.1-1988 (“POSIX.1”).
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.
August 11, 2002 | NetBSD 9.0 |