diff options
Diffstat (limited to 'doc/s6-setlock.html')
| -rw-r--r-- | doc/s6-setlock.html | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/doc/s6-setlock.html b/doc/s6-setlock.html new file mode 100644 index 0000000..bab3e23 --- /dev/null +++ b/doc/s6-setlock.html @@ -0,0 +1,65 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6: the s6-setlock program</title> + <meta name="Description" content="s6: the s6-setlock program" /> + <meta name="Keywords" content="s6 command s6-setlock lock program" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The s6-setlock program </h1> + +<p> +s6-setlock takes a lock on a file, then executes into another program. +</p> + +<h2> Interface </h2> + +<pre> + s6-setlock [ -n | -N | -t <em>timeout</em> ] [ -r | -w ] <em>file</em> <em>prog...</em> +</pre> + +<ul> + <li> s6-setlock creates <em>file</em> if it does not exist and opens it for writing. </li> + <li> It locks <em>file</em>. If it cannot take the lock for any reason, it exits 1. </li> + <li> It executes into <em>prog...</em>. </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-n</tt> : nonblocking lock. If s6-setlock cannot acquire the lock, it will +exit 1 immediately. </li> + <li> <tt>-N</tt> : blocking lock. s6-setlock will wait until it can acquire the lock. +This is the default. </li> + <li> <tt>-t <em>timeout</em> : timed lock. If s6-setlock cannot acquire +the lock after <em>timeout</em> milliseconds, it will exit 1. </li> + <li> <tt>-r</tt> : shared lock. Other shared locks on the same file will not prevent +the lock from being acquired (but an exclusive lock will). </li> + <li> <tt>-w</tt> : exclusive lock. This is the default. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> s6-setlock leaks an open file descriptor into the <em>prog</em> +execution. This is intended: the fd holds the lock, which is released +when <em>prog</em> exits. <em>prog</em> must not touch fds it does not +know about. </li> + <li> If the timed lock option is chosen, s6-setlock does not acquire the lock +itself. Instead, it spawns a <a href="libs6lock/s6lockd-helper.html">s6lockd-helper</a> +process that acquires the lock while s6-setlock controls the timeout; the +s6lockd-helper process then holds the lock and lives as long as +<em>prog</em>. </li> +</ul> + +</body> +</html> |