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28 .\" @(#)wait.2 8.2 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/lib/libc/sys/wait.2,v 1.6.2.6 2001/12/14 18:34:02 ru Exp $
30 .\" $DragonFly: src/lib/libc/sys/wait.2,v 1.4 2007/08/30 20:58:35 pavalos Exp $
40 .Nd wait for process termination
47 .Fn wait "int *status"
51 .Fn waitpid "pid_t wpid" "int *status" "int options"
53 .Fn wait3 "int *status" "int options" "struct rusage *rusage"
55 .Fn wait4 "pid_t wpid" "int *status" "int options" "struct rusage *rusage"
59 function suspends execution of its calling process until
61 information is available for a terminated child process,
62 or a signal is received.
63 On return from a successful
68 area contains termination information about the process that exited
73 call provides a more general interface for programs
74 that need to wait for certain child processes,
75 that need resource utilization statistics accumulated by child processes,
76 or that require options.
77 The other wait functions are implemented using
82 parameter specifies the set of child processes for which to wait.
85 is -1, the call waits for any child process.
89 the call waits for any child process in the process group of the caller.
92 is greater than zero, the call waits for the process with process id
96 is less than -1, the call waits for any process whose process group id
97 equals the absolute value of
102 parameter is defined below. The
104 parameter contains the bitwise OR of any of the following options.
107 option indicates that children of the current process that
108 have continued from a job control stop, by receiving a
110 signal, should also have their status reported.
114 is used to indicate that the call should not block if
115 there are no processes that wish to report status.
119 children of the current process that are stopped
121 .Dv SIGTTIN , SIGTTOU , SIGTSTP ,
125 their status reported.
129 is non-zero, a summary of the resources used by the terminated
131 children is returned (this information is currently not available
132 for stopped processes).
136 option is specified and no processes
137 wish to report status,
158 The following macros may be used to test the manner of exit of the process.
159 One of the first three macros will evaluate to a non-zero (true) value:
161 .It Fn WIFEXITED status
162 True if the process terminated normally by a call to
166 .It Fn WIFSIGNALED status
167 True if the process terminated due to receipt of a signal.
168 .It Fn WIFSTOPPED status
169 True if the process has not terminated, but has stopped and can be restarted.
170 This macro can be true only if the wait call specified the
173 or if the child process is being traced (see
177 Depending on the values of those macros, the following macros
178 produce the remaining status information about the child process:
180 .It Fn WIFCONTINUED status
181 True if the process has not terminated, and
182 has continued after a job control stop.
183 This macro can be true only if the wait call specified the
186 .It Fn WEXITSTATUS status
189 is true, evaluates to the low-order 8 bits
190 of the argument passed to
195 .It Fn WTERMSIG status
197 .Fn WIFSIGNALED status
198 is true, evaluates to the number of the signal
199 that caused the termination of the process.
200 .It Fn WCOREDUMP status
202 .Fn WIFSIGNALED status
203 is true, evaluates as true if the termination
204 of the process was accompanied by the creation of a core file
205 containing an image of the process when the signal was received.
206 .It Fn WSTOPSIG status
208 .Fn WIFSTOPPED status
209 is true, evaluates to the number of the signal
210 that caused the process to stop.
215 for a list of termination signals.
216 A status of 0 indicates normal termination.
218 If a parent process terminates without
219 waiting for all of its child processes to terminate,
220 the remaining child processes are assigned the parent
221 process 1 ID (the init process ID).
223 If a signal is caught while any of the
226 the call may be interrupted or restarted when the signal-catching routine
228 depending on the options in effect for the signal;
235 returns due to a stopped
236 or terminated child process, the process ID of the child
237 is returned to the calling process. Otherwise, a value of -1
240 is set to indicate the error.
247 returns due to a stopped
248 or terminated child process, the process ID of the child
249 is returned to the calling process.
250 If there are no children not previously awaited,
257 is specified and there are
258 no stopped or exited children,
260 If an error is detected or a caught signal aborts the call,
264 is set to indicate the error.
267 will fail and return immediately if:
270 The calling process has no existing unwaited-for
277 arguments point to an illegal address.
278 (May not be detected before exit of a child process.)
280 The call was interrupted by a caught signal,
281 or the signal did not have the
295 functions are defined by POSIX;
299 are not specified by POSIX.
303 and the ability to restart a pending
305 call are extensions to the POSIX interface.
309 function call appeared in