diff options
Diffstat (limited to 'lib/libc/sys/getpgrp.2')
-rw-r--r-- | lib/libc/sys/getpgrp.2 | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/lib/libc/sys/getpgrp.2 b/lib/libc/sys/getpgrp.2 new file mode 100644 index 0000000..f5e81a8 --- /dev/null +++ b/lib/libc/sys/getpgrp.2 @@ -0,0 +1,142 @@ +.\" Copyright (c) 1983, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)getpgrp.2 8.1 (Berkeley) 6/4/93 +.\" $FreeBSD$ +.\" +.Dd June 4, 1993 +.Dt GETPGRP 2 +.Os +.Sh NAME +.Nm getpgrp +.Nd get process group +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In unistd.h +.Ft pid_t +.Fn getpgrp void +.Ft pid_t +.Fn getpgid "pid_t pid" +.Sh DESCRIPTION +The process group of the current process is returned by +.Fn getpgrp . +The process group of the process identified by +.Fa pid +is returned by +.Fn getpgid . +If +.Fa pid +is zero, +.Fn getpgid +returns the process group of the current process. +.Pp +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. +.Pp +This system call is thus used by programs such as +.Xr csh 1 +to create +process groups +in implementing job control. +The +.Fn tcgetpgrp +and +.Fn tcsetpgrp +calls +are used to get/set the process group of the control terminal. +.Sh RETURN VALUES +The +.Fn getpgrp +system call always succeeds. +Upon successful completion, the +.Fn getpgid +system call returns the process group of the specified process; +otherwise, it returns a value of \-1 and sets +.Va errno +to indicate the error. +.Sh COMPATIBILITY +This version of +.Fn getpgrp +differs from past Berkeley versions by not taking a +.Fa "pid_t pid" +argument. +This incompatibility is required by +.St -p1003.1-90 . +.Pp +From the +.St -p1003.1-90 +Rationale: +.Pp +.Bx 4.3 +provides a +.Fn 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 V +.Fn getpgrp +suffices, and the added complexity of the +.Bx 4.3 +.Fn getpgrp +has been omitted from POSIX.1. +The old functionality is available from the +.Fn getpgid +system call. +.Sh ERRORS +The +.Fn getpgid +system call +will succeed unless: +.Bl -tag -width Er +.It Bq Er ESRCH +there is no process whose process ID equals +.Fa pid +.El +.Sh SEE ALSO +.Xr getsid 2 , +.Xr setpgid 2 , +.Xr termios 4 +.Sh STANDARDS +The +.Fn getpgrp +system call is expected to conform to +.St -p1003.1-90 . +.Sh HISTORY +The +.Fn getpgrp +system call appeared in +.Bx 4.0 . +The +.Fn getpgid +system call is derived from its usage in +.At V.4 . |