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<title>s6-linux-utils: the fstab2s6rc program</title>
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<p>
<a href="index.html">s6-linux-utils</a><br />
<a href="//skarnet.org/software/">Software</a><br />
<a href="//skarnet.org/">skarnet.org</a>
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<h1> The <tt>fstab2s6rc</tt> program </h1>
<p>
fstab2s6rc reads the <tt>/etc/fstab</tt> file, listing the filesystems and swap partitions
to mount at boot time, and builds a set of service definition directories from it, meant to
be fed to <a href="//skarnet.org/s6-rc/s6-rc-compile.html">s6-rc-compile</a>, having the
effect of mounting these partitions when run by <a href="//skarnet.org/s6-rc/s6-rc.html">s6-rc</a>.
</p>
<p>
This method has several advantages over the classic <tt>mount -a</tt>:
</p>
<ul>
<li> Parallelization. Dependencies between the mount points are respected: if <tt>/var</tt>
and <tt>/var/log</tt> are mount points in <tt>/etc/fstab</tt>, s6-rc will not attempt to
mount <tt>/var/log</tt> before <tt>/var</tt> is successfully mounted. But apart from this
necessary serialization, s6-rc will perform in parallel as much as it can. </li>
<li> Granularity. <tt>mount -a</tt> in the boot sequence treats all the mounts as one
unit; and although the output of fstab2s6rc can provide a bundle listing all the mounts,
each mount is available as a separate service. </li>
</ul>
<p>
fstab2s6rc is an <em>offline tool</em>. It does not perform mounts or unmounts itself;
it just converts the data in <tt>/etc/fstab</tt>, which is in a format usable by <tt>mount</tt>,
into a format usable — after compilation — by <a href="//skarnet.org/s6-rc/s6-rc.html">s6-rc</a>.
</p>
<h2> Interface </h2>
<pre>
fstab2s6rc [ -A | -a ] [ -U | -u ] [ -E | -e ] [ -F <em>fstab</em> ] [ -m <em>mode</em> ] [ -B <em>bundle</em> ] [ -d <em>basedep</em> ] <em>dir</em>
</pre>
<ul>
<li> fstab2s6rc creates a directory <em>dir</em> in the filesystem to host all the service definition it will create.
<em>dir</em> must not previously exist. </li>
<li> fstab2s6rc reads the <tt>/etc/fstab</tt> file. For every mount defined
in the file, it creates a subdirectory of <em>dir</em> that is a suitable definition
directory for an s6-rc service performing that mount. </li>
<li> The service is named after the mount point: the service mounting <tt>/var/log</tt>
will be called <tt>mount-var:log</tt> (slashes being replaced with colons, first slash
omitted). </li>
<li> For swap partitions, the partition named is used: the service activating swap on
<tt>/dev/sda2</tt> will be called <tt>swap-dev:sda2</tt>. </li>
</ul>
<h2> Options </h2>
<dl>
<dt> -F <em>fstab</em>, --fstab=<em>fstab</em> </dt>
<dd> Read mount point information from file <em>fstab</em> instead of <tt>/etc/fstab</tt>. </dd>
<dt> -m <em>mode</em>, --mode=<em>mode</em> </dt>
<dd> Create <em>dir</em> with permissions <em>mode</em>. <em>mode</em> is interpreted in octal. </dd>
<dt> -B <em>bundle</em>, --bundle=<em>bundle</em> </dt>
<dd> Create a bundle named <em>bundle</em> containing all the created services.
The mount point services will also be grouped under a bundle named <tt><em>bundle</em>-mounts</tt>
and the swap services will be grouped under a bundle named <tt><em>bundle</em>-swaps</tt>.
fstab lines that have the <tt>noauto</tt> option will not be included in these bundles. </dd>
<dt> -d <em>dep</em>, --base-dependency=<em>dep</em> </dt>
<dd> Add a dependency to a service named <em>dep</em> to all the created services.
This is useful e.g. in a boot sequence to ensure that the mounts will not start before
a certain point. </dd>
<dt> -A, --include-noauto </dt>
<dd> Include mount points and swaps marked <tt>noauto</tt> in the output. These
services will not be marked as essential or recommended, and they will not be included
in any bundle, but they will be there. This is the default. </dd>
<dt> -a, --exclude-noauto </dt>
<dd> Exclude mount points and swaps marked <tt>noauto</tt>. No service will be created
for these fstab entries. </dd>
<dt> -U, --without-uuid </dt>
<dd> The created services will use s6-linux-utils commands such as
<a href="s6-mount.html">s6-mount</a> and <a href="s6-swapon.html">s6-swapon</a>.
This makes the created services only depend on s6-linux-utils, but the fstab
entries must not contain util-linux-specific syntax such as <tt>UUID=</tt> or
<tt>LABEL=</tt> in place of device names (if they do, the fstab2s6rc invocation
will work, but will generate nonsensical commands, interpreting the device
names literally). This is the default. </dd>
<dt> -u, --with-uuid </dt>
<dd> The created services will use util-linux commands such as
<a href="https://man7.org/linux/man-pages/man8/mount.8.html">mount</a> and
<a href="https://man7.org/linux/man-pages/man8/swapon.8.html">swapon</a>. Running
the services will depend on having such commands installed, but syntax
for labels and uuids will be understood. </dd>
<dt> -E, --essential </dt>
<dd> Mark the services as essential, and do not create <tt>down</tt> scripts
for them. This makes services suitable to be part of a base init sequence where
all the listed filesystems are mounted early, and never unmounted until right
before the machine reboots. (<tt>noauto</tt> entries will not be marked as
essential.) This is the default. </dd>
<dt> -e, --not-essential </dt>
<dd> Mark the services as recommended rather than essential; create <tt>down</tt>
scripts to unmount the filesystem. This makes services suitable for being called
<em>later</em> than the base init sequence, as an optional part of a system's
functionality. Stopping the services will unmount the
corresponding filesystems and turn off the corresponding swap devices.
<tt>noauto</tt> entries will not be marked as recommended. </dd>
</dl>
<h2> Exit codes </h2>
<dl>
<dt> 0 </dt> <dd> Success. </dd>
<dt> 1 </dt> <dd> Invalid fstab file. </dd>
<dt> 100 </dt> <dd> Incorrect usage. </dd>
<dt> 111 </dt> <dd> System call failed. </dd>
</ul>
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