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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 $
43 .Nd wait for process termination
50 .Fn wait "int *status"
54 .Fn waitpid "pid_t wpid" "int *status" "int options"
56 .Fn wait3 "int *status" "int options" "struct rusage *rusage"
58 .Fn wait4 "pid_t wpid" "int *status" "int options" "struct rusage *rusage"
62 function suspends execution of its calling process until
64 information is available for a terminated child process,
65 or a signal is received.
66 On return from a successful
71 area contains termination information about the process that exited
76 call provides a more general interface for programs
77 that need to wait for certain child processes,
78 that need resource utilization statistics accumulated by child processes,
79 or that require options.
80 The other wait functions are implemented using
85 parameter specifies the set of child processes for which to wait.
88 is -1, the call waits for any child process.
92 the call waits for any child process in the process group of the caller.
95 is greater than zero, the call waits for the process with process id
99 is less than -1, the call waits for any process whose process group id
100 equals the absolute value of
105 parameter is defined below. The
107 parameter contains the bitwise OR of any of the following options.
111 is used to indicate that the call should not block if
112 there are no processes that wish to report status.
116 children of the current process that are stopped
118 .Dv SIGTTIN , SIGTTOU , SIGTSTP ,
122 their status reported.
126 is non-zero, a summary of the resources used by the terminated
128 children is returned (this information is currently not available
129 for stopped processes).
133 option is specified and no processes
134 wish to report status,
155 The following macros may be used to test the manner of exit of the process.
156 One of the first three macros will evaluate to a non-zero (true) value:
158 .It Fn WIFEXITED status
159 True if the process terminated normally by a call to
163 .It Fn WIFSIGNALED status
164 True if the process terminated due to receipt of a signal.
165 .It Fn WIFSTOPPED status
166 True if the process has not terminated, but has stopped and can be restarted.
167 This macro can be true only if the wait call specified the
170 or if the child process is being traced (see
174 Depending on the values of those macros, the following macros
175 produce the remaining status information about the child process:
177 .It Fn WEXITSTATUS status
180 is true, evaluates to the low-order 8 bits
181 of the argument passed to
186 .It Fn WTERMSIG status
188 .Fn WIFSIGNALED status
189 is true, evaluates to the number of the signal
190 that caused the termination of the process.
191 .It Fn WCOREDUMP status
193 .Fn WIFSIGNALED status
194 is true, evaluates as true if the termination
195 of the process was accompanied by the creation of a core file
196 containing an image of the process when the signal was received.
197 .It Fn WSTOPSIG status
199 .Fn WIFSTOPPED status
200 is true, evaluates to the number of the signal
201 that caused the process to stop.
206 for a list of termination signals.
207 A status of 0 indicates normal termination.
209 If a parent process terminates without
210 waiting for all of its child processes to terminate,
211 the remaining child processes are assigned the parent
212 process 1 ID (the init process ID).
214 If a signal is caught while any of the
217 the call may be interrupted or restarted when the signal-catching routine
219 depending on the options in effect for the signal;
226 returns due to a stopped
227 or terminated child process, the process ID of the child
228 is returned to the calling process. Otherwise, a value of -1
231 is set to indicate the error.
238 returns due to a stopped
239 or terminated child process, the process ID of the child
240 is returned to the calling process.
241 If there are no children not previously awaited,
248 is specified and there are
249 no stopped or exited children,
251 If an error is detected or a caught signal aborts the call,
255 is set to indicate the error.
258 will fail and return immediately if:
261 The calling process has no existing unwaited-for
268 arguments point to an illegal address.
269 (May not be detected before exit of a child process.)
271 The call was interrupted by a caught signal,
272 or the signal did not have the
281 functions are defined by POSIX;
285 are not specified by POSIX.
289 and the ability to restart a pending
291 call are extensions to the POSIX interface.
300 function call appeared in