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diff --git a/doc/s6-svunlink.html b/doc/s6-svunlink.html new file mode 100644 index 0000000..c2ac807 --- /dev/null +++ b/doc/s6-svunlink.html @@ -0,0 +1,90 @@ +<html> + <head> + <meta name="viewport" content="width=device-width, initial-scale=1.0" /> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6: the s6-svunlink program</title> + <meta name="Description" content="s6: the s6-svunlink program" /> + <meta name="Keywords" content="s6 command s6-svunlink supervision service stop unlink scandir servicedir" /> + <!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6</a><br /> +<a href="//skarnet.org/software/">Software</a><br /> +<a href="//skarnet.org/">skarnet.org</a> +</p> + +<h1> The s6-svunlink program </h1> + +<p> + <tt>s6-svunlink</tt> unlinks a <a href="servicedir.html">service +directory from a <a href="scandir.html">scan directory</a>, then +notify the <a href="s6-svscan.html">s6-svscan</a> that a service has +been unregistered. It waits until the <a href="s6-supervise.html">s6-supervise</a> +supervisor process has disappeared, then exits. +</p> + +<p> + The point of <tt>s6-svunlink</tt> is to help integrate existing +service directories into an existing service manager sequence and +eliminating race conditions. +</p> + +<h2> Interface </h2> + +<pre> + s6-svunlink [ -X ] [ -t <em>timeout</em> ] <em>scandir</em> <em>name</em> +</pre> + +<ul> + <li> <tt>s6-svunlink</tt> expects a running <a href="s6-svscan.html">s6-svscan</a> +process on <em>scandir</em> and a fully functional supervised service on +<a href="servicedir.html">service directory</a> in <em>scandir</em><tt>/</tt><em>name</em>, +which must be a symbolic link to a real directory located somewhere else. </li> + <li> It deletes the <em>scandir</em><tt>/</tt><em>name</em> symlink. </li> + <li> It sends a command to <a href="s6-svscan.html">s6-svscan</a> to signal it +that a service has disappeared. </li> + <li> It waits for the <a href="s6-supervise.html">s6-supervise</a> process +managing the service directory to exit. </li> + <li> It exits 0. </li> +</ul> + +<h2> Exit codes </h2> + +<ul> + <li> 0: success </li> + <li> 100: wrong usage </li> + <li> 111: system call failed </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-X</tt> : don't wait. <tt>s6-svunlink</tt> will exit right +away, without waiting for the supervisor to exit first. </li> + <li> <tt>-t <em>timeout</em></tt> : if the supervisor has not exited +after <em>timeout</em> milliseconds, <tt>s6-svlink</tt> will still exit. +The default is 0, meaning no time limit.. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> Using <tt>s6-svlink</tt> to stop services is a suboptimal pattern: +starting and stopping supervisors is a heavier operation than just stopping +services. The simpler, more efficient pattern is to simply perform +<a href="s6-svc.html">s6-svc -dwD <em>scandir</em><tt>/</tt><em>name</em>, +which only commands, and waits for, the death of the service, without +impacting the supervisor. Nevertheless, for symmetry with +<a href="s6-svlink">s6-svlink</a>, this program is provided. </li> + <li> <tt>s6-svunlink</tt> is a destructor; as is, it returns 0 even in +situations that are nominally a failure. For instance, it returns 0 even +if its timeout expires; the rationale is that there is no sensible action +for the user to do if this error is reported. <tt>s6-svunlink</tt> only +reports errors when they uncover a deeper problem in the system. </li> +</ul> + +</body> +</html> |