date and time created 91/04/12 13:40:31 by bostic

[unix-history] / usr / src / lib / libc / sys / wait.2

diff --git a/usr/src/lib/libc/sys/wait.2 b/usr/src/lib/libc/sys/wait.2
index 42829be..88f95f1 100644 (file)
--- a/usr/src/lib/libc/sys/wait.2
+++ b/usr/src/lib/libc/sys/wait.2
@@ -1,250 +1,269 @@
-.\" Copyright (c) 1980 Regents of the University of California.
-.\" All rights reserved.  The Berkeley software License Agreement
-.\" specifies the terms and conditions for redistribution.
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.

 .\"
 .\"

-.\"    @(#)wait.2      6.3 (Berkeley) %G%
+.\" %sccs.include.redist.man%

 .\"
 .\"

-.TH WAIT 2 ""
-.UC 4
-.SH NAME
-wait, waitpid, wait4, wait3 \- wait for process to terminate
-.SH SYNOPSIS
-.ft B
-.nf
-#include <sys/types.h>
-#include <sys/wait.h>
-.PP
-.ft B
-pid = wait(status)
-pid_t pid;
-int *status;
-.PP
-.ft B
-pid = waitpid(wpid, status, options)
-pid_t pid, wpid;
-int *status;
-int options;
-.PP
-.ft B
-#include <sys/time.h>
-#include <sys/resource.h>
-.PP
-.ft B
-pid = wait4(wpid, status, options, rusage)
-pid_t pid, wpid;
-int *status;
-int options;
-struct rusage *rusage;
-.PP
-.ft B
-pid = wait3(status, options, rusage)
-pid_t pid;
-int *status;
-int options;
-struct rusage *rusage;
-.fi
-.SH DESCRIPTION
-.I Wait
-causes its caller to delay until a signal is received or
-one of its child
-processes terminates.
-If any child has died since the last
-.IR wait ,
-return is immediate, returning the process id and
-exit status of one of the terminated
-children.
-If there are no children, return is immediate with
-the value \-1 returned.
-.PP
+.\"     @(#)wait.2     6.5 (Berkeley) %G%
+.\"
+.Dd 
+.Dt WAIT 2
+.Os BSD 4
+.Sh NAME
+.Nm wait ,
+.Nm waitpid ,
+.Nm wait4 ,
+.Nm wait3
+.Nd wait for process terminatation
+.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 
 On return from a successful 

-.I wait
+.Fn wait

 call, 
 the
 call, 
 the

-.I status
+.Fa status

 area contains termination information about the process that exited
 as defined below.
 area contains termination information about the process that exited
 as defined below.

-.PP
+.Pp

 The
 The

-.I wait4
+.Fn wait4

 call provides a more general interface for programs
 call provides a more general interface for programs

-that wish to wait for certain child processes,
-that wish resource utilization statistics accummulated by child processes,
+that need to wait for certain child processes,
+that need resource utilization statistics accummulated by child processes,

 or that require options.
 The other wait functions are implemented using
 or that require options.
 The other wait functions are implemented using

-.IR wait4 .
-.PP
+.Fn wait4 .
+.Pp

 The
 The

-.I wpid
+.Fa wpid

 parameter specifies the set of child processes for which to wait.
 If
 parameter specifies the set of child processes for which to wait.
 If

-.I wpid
-is \-1, the call waits for any child process.
+.Fa wpid
+is -1, the call waits for any child process.

 If
 If

-.I wpid
+.Fa wpid

 is 0,
 the call waits for any child process in the process group of the caller.
 If
 is 0,
 the call waits for any child process in the process group of the caller.
 If

-.I wpid
+.Fa wpid

 is greater than zero, the call waits for the process with process id
 is greater than zero, the call waits for the process with process id

-.IR wpid .
+.Fa wpid .

 If
 If

-.I wpid
-is less than \-1, the call waits for any process whose process group id
+.Fa wpid
+is less than -1, the call waits for any process whose process group id

 equals the absolute value of
 equals the absolute value of

-.IR wpid .
-.PP
+.Fa wpid .
+.Pp

 The
 The

-.I status
+.Fa status

 parameter is defined below.  The
 parameter is defined below.  The

-.I options
+.Fa options

 parameter contains the bitwise OR of any of the following options.
 parameter contains the bitwise OR of any of the following options.

-The WNOHANG option
+The
+.Dv WNOHANG
+option

 is used to indicate that the call should not block if
 there are no processes that wish to report status.
 is used to indicate that the call should not block if
 there are no processes that wish to report status.

-If the WUNTRACED option is set,
+If the
+.Dv WUNTRACED
+option is set,

 children of the current process that are stopped
 children of the current process that are stopped

-due to a SIGTTIN, SIGTTOU, SIGTSTP, or SIGSTOP signal also have
+due to a
+.Dv SIGTTIN , SIGTTOU , SIGTSTP ,
+or
+.Dv SIGSTOP
+signal also have

 their status reported.
 their status reported.

-.PP
+.Pp

 If
 If

-.I rusage
+.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).
 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 WNOHANG option is specified and no processes
+.Pp
+When the
+.Dv WNOHANG
+option is specified and no processes

 wish to report status, 
 wish to report status, 

-.I wait4
+.Fn wait4

 returns a 
 returns a 

-.I pid
+process id

 of 0.
 of 0.

-.PP
+.Pp

 The
 The

-.I waitpid
+.Fn waitpid

 call is identical to
 call is identical to

-.I wait4
+.Fn wait4

 with an
 with an

-.I rusage
+.Fa rusage

 value of zero.
 The older
 value of zero.
 The older

-.I wait3
+.Fn wait3

 call is the same as
 call is the same as

-.I wait4
+.Fn wait4

 with a
 with a

-.I wpid
-value of \-1.
-.PP
+.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:
 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:

-.IP WIFEXITED(status)
+.Bl -tag -width Ds
+.It Fn WIFEXITED status

 True if the process terminated normally by a call to
 True if the process terminated normally by a call to

-.IR _exit (2)
+.Xr _exit 2

 or
 or

-.IR exit (2).
-.IP WIFSIGNALED(status)
+.Xr exit 2 .
+.It Fn WIFSIGNALED status

 True if the process terminated due to receipt of a signal.
 True if the process terminated due to receipt of a signal.

-.IP WIFSTOPPED(status)
+.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
 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

-WUNTRACED
+.Dv WUNTRACED

 option
 or if the child process is being traced (see
 option
 or if the child process is being traced (see

-.IR ptrace (2)).
-.LP
+.Xr ptrace 2 ) .
+.El
+.Pp

 Depending on the values of those macros, the following macros
 produce the remaining status information about the child process:
 Depending on the values of those macros, the following macros
 produce the remaining status information about the child process:

-.IP WEXITSTATUS(status)
-If WIFEXITED(status) is true, evaluates to the low-order 8 bits
+.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
 of the argument passed to

-.IR _exit (2)
+.Xr _exit 2

 or
 or

-.IR exit (2)
+.Xr exit 2

 by the child.
 by the child.

-.IP WTERMSIG(status)
-If WIFSIGNALED(status) is true, evaluates to the number of the signal
+.It Fn WTERMSIG status
+If
+.Fn WIFSIGNALED status
+is true, evaluates to the number of the signal

 that caused the termination of the process.
 that caused the termination of the process.

-.IP WCOREDUMP(status)
-If WIFSIGNALED(status) is true, evaluates as true if the termination
+.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.
 of the process was accompanied by the creation of a core file
 containing an image of the process when the signal was received.

-.IP WSTOPSIG(status)
-If WIFSTOPPED(status) is true, evaluates to the number of the signal
+.It Fn WSTOPSIG status
+If
+.Fn WIFSTOPPED status
+is true, evaluates to the number of the signal

 that caused the process to stop.
 that caused the process to stop.

-.SH NOTES
+.El
+.Sh NOTES

 See
 See

-.IR sigaction (2)
+.Xr sigaction 2

 for a list of termination signals.
 A status of 0 indicates normal termination.
 for a list of termination signals.
 A status of 0 indicates normal termination.

-.PP
-If the parent process terminates without
-waiting on its children,
-the initialization process
-(process ID = 1)
-inherits the children.
-.PP
+.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
 If a signal is caught while any of the

-.I wait
+.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
 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

-.IR intro (2),
+.Xr intro 2 ,

 System call restart.
 System call restart.

-.SH "RETURN VALUE
-If \fIwait\fP returns due to a stopped
+.Sh RETURN VALUES
+If
+.Fn wait
+returns due to a stopped

 or terminated child process, the process ID of the child
 or terminated child process, the process ID of the child

-is returned to the calling process.  Otherwise, a value of \-1
-is returned and \fIerrno\fP is set to indicate the error.
-.PP
+is returned to the calling process.  Otherwise, a value of -1
+is returned and
+.Va errno
+is set to indicate the error.
+.Pp

 If
 If

-.IR wait4 ,
-.I wait3
+.Fn wait4 ,
+.Fn wait3

 or
 or

-.I waitpid
+.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,
 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
-.I errno
-set to [ECHILD].
-Otherwise, if WNOHANG is specified and there are
+-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,
 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 \fIerrno\fP is set to indicate the error.
-.SH ERRORS
-.I Wait
-will fail and return immediately if one or more of the following
-are true:
-.TP 15
-[ECHILD]
+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.
 The calling process has no existing unwaited-for
 child processes.

-.TP 15
-[EFAULT]
-The \fIstatus\fP or \fIrusage\fP arguments point to an illegal address.
+.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.)
 (May not be detected before exit of a child process.)

-.TP 15
-[EINTR]
+.It Bq Er EINTR

 The call was interrupted by a caught signal,
 The call was interrupted by a caught signal,

-or the signal did not have the SA_RESTART flag set.
-.SH STANDARDS
+or the signal did not have the
+.Dv SA_RESTART
+flag set.
+.El
+.Sh STANDARDS

 The
 The

-.I wait
+.Fn wait

 and
 and

-.I waitpid
+.Fn waitpid

 functions are defined by POSIX;
 functions are defined by POSIX;

-.I wait4
+.Fn wait4

 and
 and

-.I wait3
+.Fn wait3

 are not specified by POSIX.
 are not specified by POSIX.

-The WCOREDUMP macro
+The
+.Fn WCOREDUMP
+macro

 and the ability to restart a pending
 and the ability to restart a pending

-.I wait
+.Fn wait

 call are extensions to the POSIX interface.
 call are extensions to the POSIX interface.

-.SH "SEE ALSO"
-exit(2), sigaction(2)
+.Sh SEE ALSO
+.Xr exit 2 ,
+.Xr sigaction 2
+.Sh HISTORY
+A
+.Nm
+function call appeared in Version 6 AT&T UNIX.