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GETPGRP(2) FreeBSD System Calls Manual GETPGRP(2)
NAME
getpgrp -- 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 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 control. The tcgetpgrp() and
tcsetpgrp() calls are used to get/set the process group of the control
terminal.
RETURN VALUES
The 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 tak-
ing a pid_t pid argument. This incompatibility is required by ISO/IEC
9945-1:1990 (``POSIX.1'').
From the ISO/IEC 9945-1:1990 (``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() suf-
fices, and the added complexity of the 4.3BSD getpgrp() has been omitted
from POSIX.1. The old functionality is available from the getpgid() sys-
tem call.
ERRORS
The getpgid() system call will succeed unless:
[ESRCH] there is no process whose process ID equals pid
SEE ALSO
getsid(2), setpgid(2), termios(4)
STANDARDS
The getpgrp() system call is expected to conform to ISO/IEC 9945-1:1990
(``POSIX.1'').
HISTORY
The getpgrp() system call appeared in 4.0BSD. The getpgid() system call
is derived from its usage in AT&T System V.4 UNIX.
FreeBSD 6.2 June 4, 1993 FreeBSD 6.2
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This page was generated on Wed Sep 19 20:03:29 BST 2007
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