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Diffstat (limited to 'doc/wait.html')
| -rw-r--r-- | doc/wait.html | 49 |
1 files changed, 31 insertions, 18 deletions
diff --git a/doc/wait.html b/doc/wait.html index 44197a0..d38b06a 100644 --- a/doc/wait.html +++ b/doc/wait.html @@ -30,7 +30,7 @@ </p> <pre> - wait [ -I | -i ] [ -a | -o ] [ -r | -t <em>timeout</em> ] { [ <em>pids...</em> ] } <em>prog...</em> + wait [ -a | -o ] [ -u ] [ -t <em>timeout</em> ] { [ <em>pids...</em> ] } <em>prog...</em> </pre> <ul> @@ -40,36 +40,49 @@ and unquotes it. </li> <li> <tt>wait</tt> waits for every child whose pid is listed in <em>pids...</em>. If <em>pids...</em> is an empty list, it waits for every child process it has. </li> - <li><tt>wait</tt> then execs into <em>prog...</em>. </li> + <li> <tt>wait</tt> then execs into <em>prog...</em>. </li> </ul> <h2> Options </h2> <ul> - <li> <tt>-r</tt> : equivalent to <tt>-t 0</tt>. Do not -pause: only reap processes that are already dead when <tt>wait</tt> -is invoked. </li> <li> <tt>-t</tt> <em>timeout</em> : wait for a maximum of <em>timeout</em> milliseconds. If there still are living processes among <em>pids...</em> (or among <tt>wait</tt>'s children if <em>pids...</em> is an empty list), after <em>timeout</em> -milliseconds, they will not be reaped. </li> - <li> <tt>-I</tt> : loose. If <tt>wait</tt> times out while -waiting for children to die, it will still -exec into <em>prog...</em>. This is the default. </li> - <li> <tt>-i</tt> : strict. If <tt>wait</tt> times out, it -will print an error message and exit 99. </li> +milliseconds, they will not be waited for. In particular, <tt>-t0</tt> +tells <tt>wait</tt> to perform a single reaping pass on current zombies +and immediately exec into <em>prog...</em>. </li> <li> <tt>-o</tt> : wait for <em>one</em> of the listed <em>pids</em> — exec into <em>prog</em> as soon as one of the listed children dies. (If no pid is listed, wait for one child to die.) -The <tt>!</tt> environment variable will be set to the -pid that died, and the <tt>?</tt> environment variable will contain an -<a href="exitcodes.html">approximation</a> of its exit code. If no -listed child has died before <tt>wait</tt> has to exec (either because -it timed out or it has no suitable children left), the <tt>?</tt> and -<tt>!</tt> environment variables are unset. </li> <li> <tt>-a</tt> : wait for <em>all</em> of the listed <em>pids</em>. -Do not touch the <tt>!</tt> or <tt>?</tt> variables. This is the default. </li> +This is the default. </li> + <li> <tt>-u</tt> : do not export the result in the environment, +even if <tt>wait</tt> succeeds. </li> +</ul> + +<h2> Environment variables </h2> + +<p> + If the <tt>-u</tt> option has been given, <tt>wait</tt> execs into <em>prog...</em> +with the <tt>!</tt> and <tt>?</tt> environment variables unset. Same thing if an +error occurred before <tt>wait</tt> could successfully reap a zombie. +</p> + +<p> + Otherwise, the <tt>!</tt> environment variable is set to the pid of a reapt zombie, +and the <tt>?</tt> environment variable is set to its exit code. Here is how <tt>wait</tt> +decides what pid to report: +</p> + +<ul> + <li> If the <tt>-o</tt> option has been given, <tt>!</tt> is set to the pid of <em>the<em> +one zombie that has just been reapt. </li> + <li> Otherwise, if <tt>wait</tt> has been given an empty list of pids (meaning it should +wait for all of its children), then <tt>!</tt> is set to the pid of the last child it has +waited for. If there were no children, <tt>!</tt> and <tt>?</tt> are unset. </li> + <li> Otherwise, <tt>!</tt> is set to the <em>last</em> pid in the list provided to <tt>wait</tt>. </li> </ul> <h2> Notes </h2> |