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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2019-04-26 15:52:54 +0000 |
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| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2019-04-26 15:52:54 +0000 |
| commit | 1bfba3b0be32306b078f5ee527b864e758b2c77b (patch) | |
| tree | 155db6f3c01becd24d422a2e55582e222ad6a89e /doc/s6-linux-init-umountall.html | |
| parent | 9e6d0f168bf59df9cd829d6ebe63fb08ea9ae01e (diff) | |
| download | s6-linux-init-1bfba3b0be32306b078f5ee527b864e758b2c77b.tar.xz | |
Make a single hpr. Full doc, first draft.
Diffstat (limited to 'doc/s6-linux-init-umountall.html')
| -rw-r--r-- | doc/s6-linux-init-umountall.html | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/doc/s6-linux-init-umountall.html b/doc/s6-linux-init-umountall.html new file mode 100644 index 0000000..c2402fd --- /dev/null +++ b/doc/s6-linux-init-umountall.html @@ -0,0 +1,61 @@ +<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-linux-init: the s6-linux-init-umountall program</title> + <meta name="Description" content="s6-linux-init: the s6-linux-init-umountall program" /> + <meta name="Keywords" content="s6 linux administration root linux utilities umount unmount filesystem" /> + <!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6-linux-init</a><br /> +<a href="//skarnet.org/software/">Software</a><br /> +<a href="//skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>s6-linux-init-umountall</tt> program </h1> + +<p> + <tt>s6-linux-init-umountall</tt> unmounts all the filesystems. +</p> + +<h2> Interface </h2> + +<pre> + s6-linux-init-umountall +</pre> + +<ul> + <li> <tt>s6-linux-init-umountall</tt> unmounts all partitions according to <tt>/proc/mounts</tt>. +It processes <tt>/proc/mounts</tt> in the reverse order, starting with the most recently mounted +partition and ending with the root filesystem ("unmounting" the root filesystem means remounting +it read-only). </li> + <li> <tt>s6-linux-init-umountall</tt> does not touch <tt>/etc/mtab</tt>. </li> + <li> If a filesystem fails to unmount, a warning is printed to stderr, but +<tt>s6-linux-init-umountall</tt> still attempts to unmount all the other ones. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> <tt>s6-linux-init-umountall</tt> is automatically called at the very end of the shutdown procedure, +in "stage 4", i.e. after a SIGKILL has been sent to all the processes on the system, and +right before the system reboots (or halts, or is powered off). By that point, there is +no possible process that could prevent real file systems from being unmounted. </li> + <li> It is likely that some filesystems will still fail to unmount, typically +<tt>/proc</tt> and <tt>/dev</tt>. That's okay: those are pseudo-filesystems, and +will not cause data loss or a fsck if the system shuts down while they are still mounted. </li> + <li> Distributions usually provide a <tt>umount</tt> command with a <tt>-a</tt> option +to unmount all filesystems. That command is usually bloated with historical artifacts +and relies on unsafe interfaces, so it was decided not to use it. The +<a href="//skarnet.org/software/s6-linux-utils/">s6-linux-utils</a> package also +provides a <a href="//skarnet.org/software/s6-linux-utils/s6-umount.html">s6-umount</a> +command with a <tt>-a</tt> option, but adding a dependency to that package would be a +higher cost than simply reimplementing the specific functionality here. </li> +</ul> + +</body> +</html> |