Wait for an arbitrary process.
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  1. wait4 - Wait for an arbitrary process
  2. =====================================
  3. Description
  4. -----------
  5. wait4 allows its user to wait for the termination of an arbitrary
  6. process specified by its PID. It works as the standard shell command
  7. wait, but is not limited to waiting to the child processes of the
  8. current shell.
  9. On GNU/Linux systems where the Netlink interface is available, wait4 is
  10. directly informed by the kernel as soon as the target process is
  11. terminated, and the exit code of that process is used as the exit code
  12. of wait4 itself. On other systems, wait4 acts by pretending to send a
  13. signal to the target process every second; in that case, the exit code
  14. is always 0, as there is no way to retrieve the exit code of the target
  15. process.
  16. When using Netlink, wait4 must be run as setuid root, as only a
  17. privileged process can bind to an AF_NETLINK address; root privileges
  18. are dropped immediately after the bind(2) call.
  19. BSD kevent support
  20. ------------------
  21. Starting from version 0.3.0, wait4 should be able to make use of the
  22. kevent(2) call found on BSD systems, thus avoiding the signal-based
  23. fallback method on those systems. This support has currently been
  24. tested on NetBSD 6.0.1.
  25. Copying
  26. -------
  27. wait4 is distributed under the terms of the GNU General Public License,
  28. version 3 or higher. The full license is included in the COPYING file
  29. of the source distribution.
  30. Homepage and contact
  31. --------------------
  32. The project homepage, where release tarballs may be found, is located at
  33. <https://incenp.org/dvlpt/wait4.html>. The latest source code is
  34. available at <https://git.incenp.org/damien/wait4>.