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diff --git a/man2/wait4.2 b/man2/wait4.2 new file mode 100644 index 000000000..90ef0848c --- /dev/null +++ b/man2/wait4.2 @@ -0,0 +1,209 @@ +.\" Hey Emacs! This file is -*- nroff -*- source. +.\" +.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de) +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one. +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" License. +.\" +.\" Modified Sat Jul 24 13:32:44 1993 by Rik Faith (faith@cs.unc.edu) +.\" Modified Mon Jun 23 14:09:52 1997 by aeb - add EINTR. +.\" Modified Tue Jul 7 12:26:42 1998 by aeb - changed return value wait3 +.\" +.TH WAIT4 2 1997-06-23 "Linux" "Linux Programmer's Manual" +.SH NAME +wait3, wait4 \- wait for process termination, BSD style +.SH SYNOPSIS +.nf +.B #include <sys/types.h> +.B #include <sys/time.h> +.B #include <sys/resource.h> +.B #include <sys/wait.h> +.sp 2 +.BI "pid_t wait3(int *" "status" ", int " options , +.BI " struct rusage *" rusage ); +.sp +.BI "pid_t wait4(pid_t " pid ", int *" status ", int " options , +.BI " struct rusage *" rusage ); +.fi +.SH DESCRIPTION +The +.B wait3 +function suspends execution of the current process until a child has +exited, or until a signal is delivered whose action is to terminate +the current process or to call a signal handling function. If a child +has already exited by the time of the call (a so\-called "zombie" +process), the function returns immediately. Any system resources used +by the child are freed. + +The +.B wait4 +function suspends execution of the current process until a +child as specified by the +.I pid +argument has exited, or until a signal is delivered whose action is to +terminate the current process or to call a signal handling function. +If a child as requested by +.I pid +has already exited by the time of the call (a so\-called "zombie" +process), the function returns immediately. Any system resources used +by the child are freed. + +The value of +.I pid +can be one of: +.IP "< \-1" +which means to wait for any child process whose process group ID is +equal to the absolute value of +.IR pid . +.IP \-1 +which means to wait for any child process; this is equivalent to +calling +.BR wait3 . +.IP 0 +which means to wait for any child process whose process group ID is +equal to that of the calling process. +.IP "> 0" +which means to wait for the child whose process ID is equal to the +value of +.IR pid . +.PP +The value of +.I options +is a bitwise OR of zero or more of the following constants: +.TP +.B WNOHANG +which means to return immediately if no child is there to be waited +for. +.TP +.B WUNTRACED +which means to also return for children which are stopped, and whose +status has not been reported. +.PP +If +.I status +is not +.BR NULL , +.B wait3 +or +.B wait4 +store status information in the location pointed to by +.IR status . +.PP +This status can be evaluated with the following macros (these macros take +the stat buffer (an \fBint\fR) as an argument \(em not a pointer to the +buffer!): +.TP +.BI WIFEXITED( status ) +is non\-zero if the child exited normally. +.TP +.BI WEXITSTATUS( status ) +evaluates to the least significant eight bits of the return code of +the child which terminated, which may have been set as the argument to +a call to +.B exit() +or as the argument for a +.B return +statement in the main program. This macro can only be evaluated if +.B WIFEXITED +returned non\-zero. +.TP +.BI WIFSIGNALED( status ) +returns true if the child process exited because of a signal which was +not caught. +.TP +.BI WTERMSIG( status ) +returns the number of the signal that caused the child process to +terminate. This macro can only be evaluated if +.B WIFSIGNALED +returned non\-zero. +.TP +.BI WIFSTOPPED( status ) +returns true if the child process which caused the return is currently +stopped; this is only possible if the call was done using +.BR WUNTRACED . +.TP +.BI WSTOPSIG( status ) +returns the number of the signal which caused the child to stop. This +macro can only be evaluated if +.B WIFSTOPPED +returned non\-zero. +.PP +If +.I rusage +is not +.BR NULL , +the +.B struct rusage +as defined in +.I <sys/resource.h> +it points to will be filled with accounting information. See +.BR getrusage (2) +for details. +.SH "RETURN VALUE" +The process ID of the child which exited, \-1 on error +(in particular, when no unwaited-for child processes +of the specified kind exist) +or zero if +.B WNOHANG +was used and no child was available yet. +In the latter two cases +.I errno +will be set appropriately. +.SH ERRORS +.TP +.B ECHILD +No unwaited-for child process as specified does exist. +.TP +.B EINTR +if +.B WNOHANG +was not set and an unblocked signal or a +.B SIGCHLD +was caught. +.TP +.B EINVAL +Invalid value for +.I options +given for wait4. +.SH NOTES +Including +.I <sys/time.h> +is not required these days, but increases portability. +(Indeed, +.I <sys/resource.h> +defines the +.I rusage +structure with fields of type +.I struct timeval +defined in +.IR <sys/time.h> .) +.LP +The prototype for these functions is only available if +.B _BSD_SOURCE +is defined (either explicitly, or implicitly, by not defining +_POSIX_SOURCE or compiling with the -ansi flag). +.SH "CONFORMING TO" +SVr4, POSIX.1 +.SH "SEE ALSO" +.BR getrusage (2), +.BR signal (2), +.BR wait (2), +.BR signal (7) |