diff options
author | rgrimes <rgrimes@FreeBSD.org> | 1994-05-27 05:00:24 +0000 |
---|---|---|
committer | rgrimes <rgrimes@FreeBSD.org> | 1994-05-27 05:00:24 +0000 |
commit | be22b15ae2ff8d7fe06b6e14fddf0c5b444a95da (patch) | |
tree | a18a706dffa5baf86a3b12bbfb4f81caa097f349 /lib/libc/sys/wait.2 | |
parent | 2a27bd86e6002c871e3b5561a5334653bb222a77 (diff) | |
download | FreeBSD-src-be22b15ae2ff8d7fe06b6e14fddf0c5b444a95da.zip FreeBSD-src-be22b15ae2ff8d7fe06b6e14fddf0c5b444a95da.tar.gz |
BSD 4.4 Lite Lib Sources
Diffstat (limited to 'lib/libc/sys/wait.2')
-rw-r--r-- | lib/libc/sys/wait.2 | 295 |
1 files changed, 295 insertions, 0 deletions
diff --git a/lib/libc/sys/wait.2 b/lib/libc/sys/wait.2 new file mode 100644 index 0000000..c0077b1 --- /dev/null +++ b/lib/libc/sys/wait.2 @@ -0,0 +1,295 @@ +.\" Copyright (c) 1980, 1991, 1993, 1994 +.\" 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. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 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. +.\" +.\" @(#)wait.2 8.2 (Berkeley) 4/19/94 +.\" +.Dd April 19, 1994 +.Dt WAIT 2 +.Os BSD 4 +.Sh NAME +.Nm wait , +.Nm waitpid , +.Nm wait4 , +.Nm wait3 +.Nd wait for process termination +.Sh SYNOPSIS +.Fd #include <sys/types.h> +.Fd #include <sys/wait.h> +.Ft pid_t +.Fn wait "int *status" +.Fd #include <sys/time.h> +.Fd #include <sys/resource.h> +.Ft pid_t +.Fn waitpid "pid_t wpid" "int *status" "int options" +.Ft pid_t +.Fn wait3 "int *status" "int options" "struct rusage *rusage" +.Ft pid_t +.Fn wait4 "pid_t wpid" "int *status" "int options" "struct rusage *rusage" +.Sh DESCRIPTION +The +.Fn wait +function suspends execution of its calling process until +.Fa status +information is available for a terminated child process, +or a signal is received. +On return from a successful +.Fn wait +call, +the +.Fa status +area contains termination information about the process that exited +as defined below. +.Pp +The +.Fn wait4 +call provides a more general interface for programs +that need to wait for certain child processes, +that need resource utilization statistics accumulated by child processes, +or that require options. +The other wait functions are implemented using +.Fn wait4 . +.Pp +The +.Fa wpid +parameter specifies the set of child processes for which to wait. +If +.Fa wpid +is -1, the call waits for any child process. +If +.Fa wpid +is 0, +the call waits for any child process in the process group of the caller. +If +.Fa wpid +is greater than zero, the call waits for the process with process id +.Fa wpid . +If +.Fa wpid +is less than -1, the call waits for any process whose process group id +equals the absolute value of +.Fa wpid . +.Pp +The +.Fa status +parameter is defined below. The +.Fa options +parameter contains the bitwise OR of any of the following options. +The +.Dv WNOHANG +option +is used to indicate that the call should not block if +there are no processes that wish to report status. +If the +.Dv WUNTRACED +option is set, +children of the current process that are stopped +due to a +.Dv SIGTTIN , SIGTTOU , SIGTSTP , +or +.Dv SIGSTOP +signal also have +their status reported. +.Pp +If +.Fa rusage +is non-zero, a summary of the resources used by the terminated +process and all its +children is returned (this information is currently not available +for stopped processes). +.Pp +When the +.Dv WNOHANG +option is specified and no processes +wish to report status, +.Fn wait4 +returns a +process id +of 0. +.Pp +The +.Fn waitpid +call is identical to +.Fn wait4 +with an +.Fa rusage +value of zero. +The older +.Fn wait3 +call is the same as +.Fn wait4 +with a +.Fa wpid +value of -1. +.Pp +The following macros may be used to test the manner of exit of the process. +One of the first three macros will evaluate to a non-zero (true) value: +.Bl -tag -width Ds +.It Fn WIFEXITED status +True if the process terminated normally by a call to +.Xr _exit 2 +or +.Xr exit 2 . +.It Fn WIFSIGNALED status +True if the process terminated due to receipt of a signal. +.It Fn WIFSTOPPED status +True if the process has not terminated, but has stopped and can be restarted. +This macro can be true only if the wait call specified the +.Dv WUNTRACED +option +or if the child process is being traced (see +.Xr ptrace 2 ) . +.El +.Pp +Depending on the values of those macros, the following macros +produce the remaining status information about the child process: +.Bl -tag -width Ds +.It Fn WEXITSTATUS status +If +.Fn WIFEXITED status +is true, evaluates to the low-order 8 bits +of the argument passed to +.Xr _exit 2 +or +.Xr exit 2 +by the child. +.It Fn WTERMSIG status +If +.Fn WIFSIGNALED status +is true, evaluates to the number of the signal +that caused the termination of the process. +.It Fn WCOREDUMP status +If +.Fn WIFSIGNALED status +is true, evaluates as true if the termination +of the process was accompanied by the creation of a core file +containing an image of the process when the signal was received. +.It Fn WSTOPSIG status +If +.Fn WIFSTOPPED status +is true, evaluates to the number of the signal +that caused the process to stop. +.El +.Sh NOTES +See +.Xr sigaction 2 +for a list of termination signals. +A status of 0 indicates normal termination. +.Pp +If a parent process terminates without +waiting for all of its child processes to terminate, +the remaining child processes are assigned the parent +process 1 ID (the init process ID). +.Pp +If a signal is caught while any of the +.Fn wait +calls is pending, +the call may be interrupted or restarted when the signal-catching routine +returns, +depending on the options in effect for the signal; +see +.Xr intro 2 , +System call restart. +.Sh RETURN VALUES +If +.Fn wait +returns due to a stopped +or terminated child process, the process ID of the child +is returned to the calling process. Otherwise, a value of -1 +is returned and +.Va errno +is set to indicate the error. +.Pp +If +.Fn wait4 , +.Fn wait3 +or +.Fn waitpid +returns due to a stopped +or terminated child process, the process ID of the child +is returned to the calling process. +If there are no children not previously awaited, +-1 is returned with +.Va errno +set to +.Bq Er ECHILD . +Otherwise, if +.Dv WNOHANG +is specified and there are +no stopped or exited children, +0 is returned. +If an error is detected or a caught signal aborts the call, +a value of -1 +is returned and +.Va errno +is set to indicate the error. +.Sh ERRORS +.Fn Wait +will fail and return immediately if: +.Bl -tag -width Er +.It Bq Er ECHILD +The calling process has no existing unwaited-for +child processes. +.It Bq Er EFAULT +The +.Fa status +or +.Fa rusage +arguments point to an illegal address. +(May not be detected before exit of a child process.) +.It Bq Er EINTR +The call was interrupted by a caught signal, +or the signal did not have the +.Dv SA_RESTART +flag set. +.El +.Sh STANDARDS +The +.Fn wait +and +.Fn waitpid +functions are defined by POSIX; +.Fn wait4 +and +.Fn wait3 +are not specified by POSIX. +The +.Fn WCOREDUMP +macro +and the ability to restart a pending +.Fn wait +call are extensions to the POSIX interface. +.Sh SEE ALSO +.Xr exit 2 , +.Xr sigaction 2 +.Sh HISTORY +A +.Nm +function call appeared in Version 6 AT&T UNIX. |