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diff --git a/doc/s6-uevent-spawner.html b/doc/s6-uevent-spawner.html new file mode 100644 index 0000000..e9be726 --- /dev/null +++ b/doc/s6-uevent-spawner.html @@ -0,0 +1,79 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6-linux-utils: the s6-uevent-spawner program</title> + <meta name="Description" content="s6-linux-utils: the s6-uevent-spawner program" /> + <meta name="Keywords" content="s6 linux administration root utilities devd mdev udev hotplug" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6-linux-utils</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>s6-uevent-spawner</tt> program </h1> + +<p> +<tt>s6-uevent-spawner</tt> listens to its standard input for +netlink-style events, and launches a helper program for every event, +similarly to what the hotplug interface does. +</p> + +<p> + It is meant to be used together with +<a href="s6-uevent-listener.html">s6-uevent-listener</a>. +</p> + +<h2> Interface </h2> + +<pre> + s6-uevent-spawner [ -v <em>verbosity</em> ] [ -l <em>linevar</em> ] [ -t <em>l</em>:<em>t</em>:<em>k</em> ] <em>prog...</em> +</pre> + +<ul> + <li> s6-uevent-spawner listens to its stdin for a series of strings +representing kernel uevents, as formatted by +<a href="s6-uevent-listener.html">s6-uevent-listener</a>. </li> + <li> For every event it reads, it spawns <em>prog...</em> with +the event variables added to the environment, just as if <em>prog...</em> +had been registered in <tt>/proc/sys/kernel/hotplug</tt>. However, +it reads the events sequentially, and waits for a <em>prog</em> instance +to finish before spawning another one. </li> + <li> When s6-uevent-spawner receives EOF: if an instance of +<em>prog</em> is alive, it first waits for it to die. Then it exits +0. </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-v</tt> <em>verbosity</em> : be more or less verbose. +Default verbosity is 1. 0 only prints fatal error messages. 3 is too much. </li> + <li> <tt>-l</tt> <em>linevar</em> : make the event description +(i.e. the first string in the netlink message announcing the event) +available in <em>prog</em> under the environment variable <em>linevar</em>. +By default, this first string is ignored - it is not needed, all the +event information is already in the other variables. </li> + <li> <tt>-t</tt> <em>l:t:k</em> : If <em>l</em>, <em>t</em> or <em>k</em> is +specified, they specify timeouts; by default, they are infinite. +If <em>prog...</em> is still alive after <em>l</em> milliseconds, s6-devd sends +it a SIGTERM. Then, if <em>prog...</em> is still alive after <em>t</em> more +milliseconds, s6-devd sends it a SIGKILL. Then, if <em>prog...</em> is still +alive after <em>k</em> more milliseconds, s6-uevent-spawner yells and exits 99. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> The <em>prog...</em> helper should be very short-lived, +even if you are not using the <tt>-t</tt> option to s6-devd. Since helpers are +spawned sequentially, slow helpers can make events queue up and fill up +buffers. </li> +</ul> + +</body> +</html> |