June 4, 1993
freebsd-manpages
Manual pages for a GNU/kFreeBSD system
NAME
getpgrp - get process group
LIBRARY
.Lb libc
SYNOPSIS
.In unistd.h pid_t
getpgrp void pid_t getpgid pid_t pidDESCRIPTION
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 taking a pid_t pid argument. This incompatibility is required by -p1003.1-90.
From the -p1003.1-90 Rationale:
BSD 4.3 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 V getpgrp suffices, and the added complexity of the BSD 4.3 getpgrp has been omitted from POSIX.1. The old functionality is available from the getpgid system call.ERRORS
The
getpgid system call will succeed unless:
[ESRCH] |
|
| there is no process whose process ID equals pid | |
SEE ALSO
STANDARDS
The
getpgrp system call is expected to conform to -p1003.1-90.HISTORY
The
getpgrp system call appeared in BSD 4.0 . The getpgid system call is derived from its usage in AT&T V.4 .