s6-linux-utils
Software
skarnet.org

The fstab2s6rc program

fstab2s6rc reads the /etc/fstab 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 s6-rc-compile, having the effect of mounting these partitions when run by s6-rc.

This method has several advantages over the classic mount -a:

• Parallelization. Dependencies between the mount points are respected: if /var and /var/log are mount points in /etc/fstab, s6-rc will not attempt to mount /var/log before /var is successfully mounted. But apart from this necessary serialization, s6-rc will perform in parallel as much as it can.
• Granularity. mount -a 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.

fstab2s6rc is an offline tool. It does not perform mounts or unmounts itself; it just converts the data in /etc/fstab, which is in a format usable by mount, into a format usable — after compilation — by s6-rc.

Interface

     fstab2s6rc [ -A | -a ] [ -U | -u ] [ -E | -e ] [ -F fstab ] [ -m mode ] [ -B bundle ] [ -d basedep ] dir

• fstab2s6rc creates a directory dir in the filesystem to host all the service definition it will create. dir must not previously exist.
• fstab2s6rc reads the /etc/fstab file. For every mount defined in the file, it creates a subdirectory of dir that is a suitable definition directory for an s6-rc service performing that mount.
• The service is named after the mount point: the service mounting /var/log will be called mount-var:log (slashes being replaced with colons, first slash omitted).
• For swap partitions, the partition named is used: the service activating swap on /dev/sda2 will be called swap-dev:sda2.

Options

-F fstab, --fstab=fstab

Read mount point information from file fstab instead of /etc/fstab.

-m mode, --mode=mode

Create dir with permissions mode. mode is interpreted in octal.

-B bundle, --bundle=bundle

Create a bundle named bundle containing all the created services. The mount point services will also be grouped under a bundle named bundle-mounts and the swap services will be grouped under a bundle named bundle-swaps. fstab lines that have the noauto option will not be included in these bundles.

-d dep, --base-dependency=dep

Add a dependency to a service named dep 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.

-A, --include-noauto

Include mount points and swaps marked noauto 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.

-a, --exclude-noauto

Exclude mount points and swaps marked noauto. No service will be created for these fstab entries.

-U, --without-uuid

The created services will use s6-linux-utils commands such as s6-mount and s6-swapon. This makes the created services only depend on s6-linux-utils, but the fstab entries must not contain util-linux-specific syntax such as UUID= or LABEL= 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.

-u, --with-uuid

The created services will use util-linux commands such as mount and swapon. Running the services will depend on having such commands installed, but syntax for labels and uuids will be understood.

-E, --essential

Mark the services as essential, and do not create down 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. (noauto entries will not be marked as essential.) This is the default.

-e, --not-essential

Mark the services as recommended rather than essential; create down scripts to unmount the filesystem. This makes services suitable for being called later 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. noauto entries will not be marked as recommended.

Exit codes

0

Success.

1

Invalid fstab file.

100

Incorrect usage.

111

System call failed.