Manpages - wait4.2

wait3, wait4 - wait for process to change state, BSD style

  #include <sys/wait.h>

  pid_t wait3(int *wstatus, int options, struct rusage *rusage);
  pid_t wait4(pid_t pid, int *wstatus, int options,
   struct rusage *rusage);

Feature Test Macro Requirements for glibc (see *feature_test_macros*(7)):

*wait3*():

      Since glibc 2.26:
          _DEFAULT_SOURCE
              || (_XOPEN_SOURCE >= 500 &&
                  ! (_POSIX_C_SOURCE >= 200112L
                     || _XOPEN_SOURCE >= 600))
      From glibc 2.19 to 2.25:
          _DEFAULT_SOURCE || _XOPEN_SOURCE >= 500
      Glibc 2.19 and earlier:
          _BSD_SOURCE || _XOPEN_SOURCE >= 500

*wait4*():

      Since glibc 2.19:
          _DEFAULT_SOURCE
      Glibc 2.19 and earlier:
          _BSD_SOURCE

These functions are nonstandard; in new programs, the use of *waitpid*(2) or *waitid*(2) is preferable.

The *wait3*() and *wait4*() system calls are similar to *waitpid*(2), but additionally return resource usage information about the child in the structure pointed to by rusage.

Other than the use of the rusage argument, the following *wait3*() call:

  wait3(wstatus, options, rusage);

is equivalent to:

  waitpid(-1, wstatus, options);

Similarly, the following *wait4*() call:

  wait4(pid, wstatus, options, rusage);

is equivalent to:

  waitpid(pid, wstatus, options);

In other words, *wait3*() waits of any child, while *wait4*() can be used to select a specific child, or children, on which to wait. See *wait*(2) for further details.

If rusage is not NULL, the struct rusage to which it points will be filled with accounting information about the child. See *getrusage*(2) for details.

As for *waitpid*(2).

As for *waitpid*(2).

4.3BSD.

SUSv1 included a specification of *wait3*(); SUSv2 included *wait3*(), but marked it LEGACY; SUSv3 removed it.

Including <sys/time.h> is not required these days, but increases portability. (Indeed, <sys/resource.h> defines the rusage structure with fields of type struct timeval defined in <sys/time.h>.)

*fork*(2), *getrusage*(2), *sigaction*(2), *signal*(2), *wait*(2), *signal*(7)

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