diff options
| author | Laurent Bercot <ska-skaware@skarnet.org> | 2026-06-08 00:56:35 +0000 |
|---|---|---|
| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2026-06-08 00:56:35 +0000 |
| commit | 06d97dd40108bc685a4fab846cc156827534d15b (patch) | |
| tree | e14c09b567bd75d1994a95b5a56f7fd9360fac50 /doc | |
| parent | af9550cfe7ea35590d9c8e246ebeaa32f6469966 (diff) | |
| download | s6-06d97dd40108bc685a4fab846cc156827534d15b.tar.gz | |
Add s6-svscanboot doc
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/s6-svscanboot.html | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/doc/s6-svscanboot.html b/doc/s6-svscanboot.html new file mode 100644 index 0000000..5b2f225 --- /dev/null +++ b/doc/s6-svscanboot.html @@ -0,0 +1,131 @@ +<html> + <head> + <meta name="viewport" content="width=device-width, initial-scale=1.0" /> + <meta name="color-scheme" content="dark light" /> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6: the s6-svscanboot program</title> + <meta name="Description" content="s6: the s6-svscanboot program" /> + <meta name="Keywords" content="s6 command s6-svscanboot scandir supervision supervise svscan logging catch-all directory" /> + <!-- <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/">www.skarnet.org</a> +</p> + +<h1> The s6-svscanboot program </h1> + +<p> +<tt>s6-svscanboot</tt> starts a supervision tree, spearheaded by +<a href="s6-svscan.html">s6-svscan</a>, while logging its own output, +as well as the output of the tree's <a href="s6-supervise.html">s6-supervise</a> +processes, into a catch-all logger that it itself supervises. +</p> + +<p> +In other words, it starts a self-sufficient, self-contained supervision tree, +that does not leak logs &emdash; apart from exceptionally rare error messages +from the catch-all logger itself. +</p> + +<p> +<tt>s6-svscanboot</tt> is meant to be used when an external service manager +needs to start an s6 supervision tree. It prevents the supervision tree's logs +from either flooding the upper service manager or being lost entirely. +</p> + +<h2> Interface </h2> + +<pre> + s6-svscanboot [ -c <em>devconsole</em> ] [ -D <em>catchalldir</em> ] [ -m <em>catchallmode</em> ] [ -l <em>catchalluser</em> ] [ -o <em>catchalloptions</em> ] [ -d <em>notif</em> ] [ -X <em>consoleholder</em> ] [ -C <em>services_max</em> ] [ -L <em>name_max</em> ] [ -t <em>rescan</em> ] <em>scandir</em> +</pre> + +<ul> + <li> <tt>s6-svscanboot</tt> creates the <tt>/run/uncaught-logs</tt> directory +if it does not already exist, and changes its mode to 02750. </li> + <li> It creates the <em>scandir</em> directory if it does not exist yet. + <li> It deletes any pre-existing <tt><em>scandir</em>/s6-svscan-log</tt> +directory, then recreates it as a suitable +<a href="servicedir.html">service directory</a> running +<a href="s6-log.html">s6-log</a> to log to <tt>/run/uncaught-logs</tt>. This +is the service that will serve as the catch-all logger. </li> + <li> It redirects its standard input to <tt>/dev/null</tt>, and its standard +output and error to a named pipe that will be read by the catch-all logger. +It performs the necessary magic so that the redirection happens even though +that named pipe has no reader yet. </li> + <li> It execs into <a href="s6-svscan.html">s6-svscan</a>, running on +<em>scandir</em>. </li> +</ul> + +<h2> Exit codes </h2> + +<dl> +<dt> 100 </dt> <dd> Wrong usage </dd> +<dt> 111 </dt> <dd> System call failure </dd> +</dl> + +<p> +On success, <tt>s6-svscanboot</tt> does not exit, but execs into +<a href="s6-svscan.html">s6-svscan</a> instead, which is supposed to remain +running until the administrator decides to stop it or the machine shuts down. +</p> + + +<h2> Options </h2> + +<dl> + <dt> <tt>-c <em>console</em></tt>, <tt>--console=<em>console</em></tt> </dt> + <dd> Send the catch-all logger's error messages to device <em>console</em>. These +will be the only error messages from the supervision tree that will not go into +the catch-all logger. By default, this device is whatever <tt>s6-svscanboot</tt> +stderr points to at invocation time. </dd> + + <dt> <tt>-D <em>dir</em></tt>, <tt>--catchall-directory=<em>dir</em></tt> </dt> + <dd> The directory where the <a href="s6-log.html">s6-log</a> catch-all will write +and rotate the supervision tree's logs. Default is <strong><tt>/run/uncaught-logs</tt></strong>. </dd> + + <dt> <tt>-m <em>mode</em></tt>, <tt>--catchall-mode=<em>mode</em></tt> <dt> + <dd> What permissions the catch-all directory shall have. Default is <strong>02750</strong>. </dd> + + <dt> <tt>-l <em>user</em></tt>, <tt>--catchall-user=<em>user</em></tt> <dt> + <dd> What user the catch-all logger shall run as. Default is the same user as +the supervision tree, i.e. the user that launched <tt>s6-svscanboot</tt>. This +option should only be used by root. </dd> + + <dt> <tt>-o <em>options</em></tt>, <tt>--catchall-options=<em>options</em></tt> <dt> + <dd> What control and selection directives the <a href="s6-log.html">s6-log</a> program +shall use for logging its input. Directives should be separated by spaces. The +<em>options</em> string will appear verbatim in the <tt><em>scandir</em>/s6-svscan-log/run</tt> +script, so caution should be used when using this option. Default is <strong><tt>t</tt></strong>. </dd> + + <dt> <tt>-d <em>notif</em></tt>, <tt>--notification-fd=<em>notif</em></tt> </dt> + <dd> Notify file descriptor <em>notif</em> when <a href="s6-svscan.html">s6-svscan</a> is ready. +This option is passed directly to <a href="s6-svscan.html">s6-svscan</a>. </dd> + + <dt> <tt>-C <em>services_max</em></tt>, <tt>--services-max=<em>services_max</em></tt> </dt> + <dd> Maintain services for up to <em>services_max</em> service directories, including loggers. +This option is passed directly to <a href="s6-svscan.html">s6-svscan</a>. </dd> + + <dt> <tt>-L <em>name_max</em></tt>, <tt>--name-max=<em>name_max</em></tt> </dt> + <dd> The maximum length of a name in the scan directory. +This option is passed directly to <a href="s6-svscan.html">s6-svscan</a>. </dd> + + <dt> <tt>-t <em>rescan</em></tt>, <tt>--timeout=<em>rescan</em></tt> </dt> + <dd> Perform a scan every <em>rescan</em> milliseconds. +This option is passed directly to <a href="s6-svscan.html">s6-svscan</a>. </dd> +</dl> + +<h2> Notes </h2> + +<ul> + <li> <tt>s6-svscanboot</tt> is only useful in situations where it is +beneficial for a supervision tree to log its own output. In other situations, +it is better to launch <a href="s6-svscan.html">s6-svscan</a> directly. </li> +</ul> + +</body> +</html> |