439 lines
12 KiB
HTML
439 lines
12 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<html>
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<head>
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<title>runit - Frequently asked questions</title>
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</head>
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<body>
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<a href="http://smarden.org/pape/">G. Pape</a><br>
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<a href="index.html">runit</a><br>
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<hr>
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<h1>runit - Frequently asked questions</h1>
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<hr>
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<a href="#what">
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What's runit, why is it that different
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</a><br>
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<a href="#help">
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I need some help with runit, what should I do
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</a><br>
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<!--
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<a href="#service">
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What is a service, what a service daemon
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</a><br>
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-->
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<a href="#license">
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What's the license, is runit free software
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</a><br>
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<p>
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<a href="#run">
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How do I run a service under runit service supervision
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</a><br>
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<a href="#create">
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How do I create a new service directory
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</a><br>
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<!--
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<a href="#log">
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What is a log service
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</a><br>
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-->
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<a href="#createlog">
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How do I create a new service directory with an appendant log service
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</a><br>
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<a href="#tell">
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How do I tell runit about a new service
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</a><br>
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<a href="#control">
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How do I start, stop, or restart a service
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</a><br>
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<a href="#signal">
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How can I send signals to a service daemon
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</a><br>
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<a href="#status">
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How can I query the status of a service
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</a><br>
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<a href="#remove">
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How do I remove a service
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</a><br>
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<p>
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<a href="#depends">
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How do I make a service depend on another service
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</a><br>
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<!--
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<a href="#strongdepends">
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How can I make a service affect a dependant service
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</a><br>
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-->
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<p>
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<a href="#runlevels">
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What about runlevels
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</a><br>
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<a href="#lsb">
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What about LSB init scripts compliance
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</a><br>
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<p>
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<a href="#user">
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Is it possible to allow a user other than root to control a service
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</a><br>
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<a href="#userservices">
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Does runit support user-specific services?
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</a><br>
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<a href="#readonlyfs">
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Does runit work on a read-only filesystem
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</a><br>
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<hr>
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<a name="what"><h3>
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What's runit, why is it that different
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</h3></a>
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What is this runit init scheme about?
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Why is it that different from sysvinit and other init schemes?
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<p>
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Answer:
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Please see the <a href="index.html">introduction</a>, and web page about
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runit's <a href="benefits.html">benefits</a>.
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<hr>
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<a name="help"><h3>
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I need some help with runit, what should I do
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</h3></a>
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I have a question, runit is doing something wrong, or I'm doing something
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wrong, what should I do?
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<p>
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Answer:
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First see the documentation, especially this list of
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<a href="faq.html">frequently asked questions</a>, and the man pages
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if you have a question about a specific runit program.
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If that still doesn't answer your question, try to search the
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<a href="http://news.gmane.org/gmane.comp.sysutils.supervision.general">
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supervision mailing list archive</a>.
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Finally, if this fails, feel free to post your question to the
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<a href="http://skarnet.org/lists/">supervision mailing list</a>.
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<!--
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<hr>
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<a name="service"><h3>
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What is a service, what a service daemon
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</h3></a>
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The runit documentation talks about services and service daemons.
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What actually is a service, and what a service daemon?
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<p>
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Answer:
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-->
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<hr>
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<a name="license"><h3>
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What's the license, is runit free software
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</h3></a>
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I would like to distribute runit, in source and binary form.
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Am I allowed to do so?
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<p>
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Answer:
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runit is free software, it's licensed under a three-clause BSD alike
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license.
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See the file <tt>package/COPYING</tt> in the runit tarball.
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<hr>
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<a name="run"><h3>
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How do I run a service under runit service supervision
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</h3></a>
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I want a service to be run under runit service supervision, so that it's
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automatically started on system boot, and supervised while system uptime.
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How does that work?
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<p>
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Answer:
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runit doesn't use the usual <tt>/etc/init.d/</tt> init script interface,
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but uses a directory per service.
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To integrate a service into the runit init scheme,
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<a href="#create">create a service directory</a> for the service, and
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<a href="#tell">tell runit</a> about it.
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<hr>
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<a name="create"><h3>
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How do I create a new service directory
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</h3></a>
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How do I create a service directory for the use with runit?
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<p>
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Answer:
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Service directories usually are placed into the <tt>/etc/sv/</tt>
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directory.
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Create a new directory for your service in <tt>/etc/sv/</tt>, put a
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<tt>./run</tt> script into it, and make the script executable.
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Note that for the use with runit,
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<a href="#service">service daemons</a> must not put themself into the
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background, but must run in the foreground.
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Here's a simple example for a <tt>getty</tt> service:
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<pre>
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$ cat /etc/sv/getty-2/run
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#!/bin/sh
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exec getty 38400 tty2 linux
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$
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</pre>
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Note the <tt>exec</tt> in the last line, it tells the shell that
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interprets the script to replace itself with the service daemon
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<tt>getty</tt>; this is necessary to make
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<a href="#control">controlling the service</a> work properly.
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<!--
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<hr>
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<a name="log"><h3>
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What is a log service
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</h3></a>
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Additionally to supervising a service runit can supervise an appendant
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log service.
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What does that mean?
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<p>
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Answer:
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-->
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<hr>
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<a name="createlog"><h3>
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How do I create a new service directory with an appendant log service
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</h3></a>
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How do I create a service directory with an appendant log service for the
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use with runit?
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<p>
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Answer:
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First <a href="#create">create the service directory</a> for the service.
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Then create a subdirectory <tt>./log</tt> in the service directory, again
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put a <tt>./run</tt> script into it, and make the script executable.
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The <tt>./run</tt> script must run a service logging daemon, normally
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this is the <a href="svlogd.8.html">svlogd</a> program.
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See the <a href="runsv.8.html">runsv</a> man page for details.
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Here's an example of a <tt>./log/run</tt> script:
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<pre>
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$ cat /etc/sv/socklog-klog/log/run
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#!/bin/sh
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exec chpst -ulog svlogd -tt ./main
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$
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</pre>
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<hr>
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<a name="tell"><h3>
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How do I tell runit about a new service
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</h3></a>
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I created a service directory for a service that should run under runit
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service supervision.
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How do I tell runit about the new service directory, so that it picks
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up and runs the service by default?
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<p>
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Answer:
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Create a symbolic link in <tt>/service/</tt> pointing to the service
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directory, runit will pick up the service within the next five seconds,
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and automatically start it on system boot.
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E.g.:
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<pre>
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# ln -s /etc/sv/getty-2 /service/
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</pre>
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<hr>
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<a name="control"><h3>
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How do I start, stop, or restart a service
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</h3></a>
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I want to stop a service temporarily, and probably restart is later, or
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I want to have it restarted immediately.
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How can I control a service running under runit service supervision?
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<p>
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Answer:
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Use the <a href="sv.8.html">sv</a> program.
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E.g., to restart the <tt>socklog-unix</tt> service, do:
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<pre>
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# sv restart socklog-unix
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</pre>
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<hr>
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<a name="signal"><h3>
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How can I send signals to a service daemon
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</h3></a>
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I want to send a service daemon the HUP signal, to have it re-read its
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configuration, or I want to send it the INT signal.
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How can a send signals to a service daemon?
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<p>
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Answer:
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Use the <a href="sv.8.html">sv</a> program.
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E.g., to send the <tt>dhcp</tt> service the HUP signal, do:
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<pre>
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# sv hup dhcp
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</pre>
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<hr>
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<a name="status"><h3>
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How can I query the status of a service
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</a></h3>
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I want to now the status of a service, whether it is up and available,
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or down as requested, or so.
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How can I find out this information?
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<p>
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Answer:
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User the <a href="sv.8.html">sv</a> program.
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E.g., to query or check the status of the <tt>socklog-unix</tt> service,
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do:
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<pre>
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# sv status socklog-unix
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</pre>
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or
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<pre>
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# sv check socklog-unix
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</pre>
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<hr>
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<a name="remove"><h3>
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How do I remove a service
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</h3></a>
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I want to remove a service that currently runs under runit service
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supervision.
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How do I tell runit?
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<p>
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Answer:
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Remove the symbolic link in <tt>/service/</tt> pointing to the service
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directory, runit recognizes the removed service within the next five
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seconds, then stops the service, the optional log service, and finally the
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supervisor process.
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E.g.:
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<pre>
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# rm /service/getty-2
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</pre>
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<hr>
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<a name="depends"><h3>
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How do I make a service depend on another service
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</a></h3>
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I have a service that needs another service to be available before it can
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start.
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How can I tell runit about this dependency?
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<p>
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Answer:
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Make sure in the <tt>./run</tt> script of the dependant service that the
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service it depends on is available before the service daemon starts.
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The <a href="sv.8.html">sv</a> program can be used for that.
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E.g. the <tt>cron</tt> service wants the <tt>socklog-unix</tt> system
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logging service to be available before starting the <tt>cron</tt> service
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daemon, so no logs get lost:
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<pre>
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$ cat /etc/sv/cron/run
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#!/bin/sh
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sv start socklog-unix || exit 1
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exec cron -f
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$
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</pre>
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See also the <a href="dependencies.html">documentation</a>.
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<!--
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<hr>
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<a name="strongdepends"><h3>
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How can I make a service affect a dependant service
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</a></h3>
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<a href="#depends">This dependency</a> is not enough.
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I have a service that needs to be stopped or restarted, whenever a service
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it depends on stops or restarts.
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How can I tell runit about that a service affects a dependant service in
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such a way?
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<p>
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Answer:
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First think about whether you really need this, it almost never should be
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necessary.
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If you really need this,
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-->
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<hr>
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<a name="runlevels"><h3>
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What about runlevels
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</a></h3>
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Other init schemes support runlevels, what about runit?
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<p>
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Answer:
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runit supports runlevels, even more flexible than traditional init schemes.
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See <a href="runlevels.html">the documentation</a>.
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<hr>
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<a name="lsb"><h3>
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What about LSB init scripts compliance
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</a></h3>
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I know about the <a href="sv.8.html">sv</a> program to control a service,
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but have applications that rely on the <tt>/etc/init.d/</tt> scripts
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interface as defined through LSB.
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Do I need to change the application to work with runit?
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<p>
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Answer:
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You don't need to change the application.
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The <a href="sv.8.html">sv</a> program supports the <tt>/etc/init.d/</tt>
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script interface
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<a href="http://refspecs.freestandards.org/LSB_2.1.0/LSB-generic/LSB-generic/iniscrptact.html">
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as defined through LSB</a>.
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To make this script interface work for a service, create a symbolic link
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in <tt>/etc/init.d/</tt>, named as the service daemon, pointing to the
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<a href="sv.8.html">sv</a> program, e.g. for the <tt>cron</tt> service:
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<pre>
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# ln -s /bin/sv /etc/init.d/cron
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# /etc/init.d/cron restart
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ok: run: cron: (pid 5869) 0s
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#
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</pre>
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|
|
<hr>
|
||
|
|
<a name="user"><h3>
|
||
|
|
Is it possible to allow a user other than root to control a service
|
||
|
|
</a></h3>
|
||
|
|
Using the <a href="sv.8.html">sv</a> program to control a service, or query
|
||
|
|
its status informations, only works as root.
|
||
|
|
Is it possible to allow non-root users to control a service too?
|
||
|
|
<p>
|
||
|
|
Answer:
|
||
|
|
Yes, you simply need to adjust file system permissions for the
|
||
|
|
<tt>./supervise/</tt> subdirectory in the service directory.
|
||
|
|
E.g.: to allow the user <tt>burdon</tt> to control the service
|
||
|
|
<tt>dhcp</tt>, change to the <tt>dhcp</tt> service directory, and do
|
||
|
|
<pre>
|
||
|
|
# chmod 755 ./supervise
|
||
|
|
# chown burdon ./supervise/ok ./supervise/control ./supervise/status
|
||
|
|
</pre>
|
||
|
|
This works similarly with groups, of course.
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<a name="userservices"><h3>
|
||
|
|
Does runit support user-specific services?
|
||
|
|
</a></h3>
|
||
|
|
It's very nice to simply
|
||
|
|
<a href="#tell">create symbolic links</a> to add system-wide services.
|
||
|
|
Does this work for user-specific services too?
|
||
|
|
<p>
|
||
|
|
Answer:
|
||
|
|
Yes.
|
||
|
|
E.g.: to provide the user <tt>floyd</tt> with facility to manage services
|
||
|
|
through <tt>~/service/</tt>, <a href="#createlog">create a service</a>
|
||
|
|
<tt>runsvdir-floyd</tt> with the following run script and a usual log/run
|
||
|
|
script, and <a href="#tell">tell runit</a> about the service
|
||
|
|
<pre>
|
||
|
|
#!/bin/sh
|
||
|
|
exec 2>&1
|
||
|
|
exec chpst -ufloyd runsvdir /home/floyd/service
|
||
|
|
</pre>
|
||
|
|
Now <tt>floyd</tt> can create services on his own, and manage them through
|
||
|
|
symbolic links in <tt>~/service/</tt> to have them run under his user id.
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<a name="readonlyfs"><h3>
|
||
|
|
Does runit work on a read-only filesystem
|
||
|
|
</a></h3>
|
||
|
|
On my system <tt>/etc/</tt> is mounted read-only by default.
|
||
|
|
runit uses many files in <tt>/etc/</tt> it needs to write to, like
|
||
|
|
<tt>/etc/runit/stopit</tt>, and the <tt>./supervise/</tt>
|
||
|
|
subdirectories in the service directories.
|
||
|
|
How can I make runit work on my system?
|
||
|
|
<p>
|
||
|
|
Answer:
|
||
|
|
Use symbolic links, runit deals with them well, even with dangling
|
||
|
|
symlinks.
|
||
|
|
E.g., make a ramdisk available at a moint point, say <tt>/var/run/</tt>,
|
||
|
|
and create symbolic links for the files and directories that runit needs
|
||
|
|
to write access to pointing into <tt>/var/run/</tt>:
|
||
|
|
<pre>
|
||
|
|
# ln -s /var/run/runit.stopit /etc/runit/stopit
|
||
|
|
# ln -s /var/run/sv.getty-2 /etc/sv/getty-2/supervise
|
||
|
|
</pre>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<address><a href="mailto:pape@smarden.org">
|
||
|
|
Gerrit Pape <pape@smarden.org>
|
||
|
|
</a></address>
|
||
|
|
</body>
|
||
|
|
</html>
|