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32 .\" @(#)wait.2 8.2 (Berkeley) 4/19/94
33 .\" $FreeBSD: src/lib/libc/sys/wait.2,v 1.6.2.6 2001/12/14 18:34:02 ru Exp $
34 .\" $DragonFly: src/lib/libc/sys/wait.2,v 1.4 2007/08/30 20:58:35 pavalos Exp $
44 .Nd wait for process termination
51 .Fn wait "int *status"
55 .Fn waitpid "pid_t wpid" "int *status" "int options"
57 .Fn wait3 "int *status" "int options" "struct rusage *rusage"
59 .Fn wait4 "pid_t wpid" "int *status" "int options" "struct rusage *rusage"
63 function suspends execution of its calling process until
65 information is available for a terminated child process,
66 or a signal is received.
67 On return from a successful
72 area contains termination information about the process that exited
77 call provides a more general interface for programs
78 that need to wait for certain child processes,
79 that need resource utilization statistics accumulated by child processes,
80 or that require options.
81 The other wait functions are implemented using
86 parameter specifies the set of child processes for which to wait.
89 is -1, the call waits for any child process.
93 the call waits for any child process in the process group of the caller.
96 is greater than zero, the call waits for the process with process id
100 is less than -1, the call waits for any process whose process group id
101 equals the absolute value of
106 parameter is defined below. The
108 parameter contains the bitwise OR of any of the following options.
111 option indicates that children of the current process that
112 have continued from a job control stop, by receiving a
114 signal, should also have their status reported.
118 is used to indicate that the call should not block if
119 there are no processes that wish to report status.
123 children of the current process that are stopped
125 .Dv SIGTTIN , SIGTTOU , SIGTSTP ,
129 their status reported.
133 is non-zero, a summary of the resources used by the terminated
135 children is returned (this information is currently not available
136 for stopped processes).
140 option is specified and no processes
141 wish to report status,
162 The following macros may be used to test the manner of exit of the process.
163 One of the first three macros will evaluate to a non-zero (true) value:
165 .It Fn WIFEXITED status
166 True if the process terminated normally by a call to
170 .It Fn WIFSIGNALED status
171 True if the process terminated due to receipt of a signal.
172 .It Fn WIFSTOPPED status
173 True if the process has not terminated, but has stopped and can be restarted.
174 This macro can be true only if the wait call specified the
177 or if the child process is being traced (see
181 Depending on the values of those macros, the following macros
182 produce the remaining status information about the child process:
184 .It Fn WIFCONTINUED status
185 True if the process has not terminated, and
186 has continued after a job control stop.
187 This macro can be true only if the wait call specified the
190 .It Fn WEXITSTATUS status
193 is true, evaluates to the low-order 8 bits
194 of the argument passed to
199 .It Fn WTERMSIG status
201 .Fn WIFSIGNALED status
202 is true, evaluates to the number of the signal
203 that caused the termination of the process.
204 .It Fn WCOREDUMP status
206 .Fn WIFSIGNALED status
207 is true, evaluates as true if the termination
208 of the process was accompanied by the creation of a core file
209 containing an image of the process when the signal was received.
210 .It Fn WSTOPSIG status
212 .Fn WIFSTOPPED status
213 is true, evaluates to the number of the signal
214 that caused the process to stop.
219 for a list of termination signals.
220 A status of 0 indicates normal termination.
222 If a parent process terminates without
223 waiting for all of its child processes to terminate,
224 the remaining child processes are assigned the parent
225 process 1 ID (the init process ID).
227 If a signal is caught while any of the
230 the call may be interrupted or restarted when the signal-catching routine
232 depending on the options in effect for the signal;
239 returns due to a stopped
240 or terminated child process, the process ID of the child
241 is returned to the calling process. Otherwise, a value of -1
244 is set to indicate the error.
251 returns due to a stopped
252 or terminated child process, the process ID of the child
253 is returned to the calling process.
254 If there are no children not previously awaited,
261 is specified and there are
262 no stopped or exited children,
264 If an error is detected or a caught signal aborts the call,
268 is set to indicate the error.
271 will fail and return immediately if:
274 The calling process has no existing unwaited-for
281 arguments point to an illegal address.
282 (May not be detected before exit of a child process.)
284 The call was interrupted by a caught signal,
285 or the signal did not have the
299 functions are defined by POSIX;
303 are not specified by POSIX.
307 and the ability to restart a pending
309 call are extensions to the POSIX interface.
313 function call appeared in