NAME

       systemd-fstab-generator - Unit generator for /etc/fstab

SYNOPSIS

       /lib/systemd/system-generators/systemd-fstab-generator

DESCRIPTION

       systemd-fstab-generator is a generator that translates /etc/fstab (see fstab(5) for
       details) into native systemd units early at boot and when configuration of the system
       manager is reloaded. This will instantiate mount and swap units as necessary.

       The passno field is treated like a simple boolean, and the ordering information is
       discarded. However, if the root file system is checked, it is checked before all the other
       file systems.

       See systemd.mount(5) and systemd.swap(5) for more information about special /etc/fstab
       mount options this generator understands.

       One special topic is handling of symbolic links. Historical init implementations supported
       symlinks in /etc/fstab. Because mount units will refuse mounts where the target is a
       symbolic link, this generator will resolve any symlinks as far as possible when processing
       /etc/fstab in order to enhance backwards compatibility. If a symlink target does not exist
       at the time that this generator runs, it is assumed that the symlink target is the final
       target of the mount.

       systemd-fstab-generator implements systemd.generator(7).

KERNEL COMMAND LINE

       systemd-fstab-generator understands the following kernel command line parameters:

       fstab=, rd.fstab=
           Takes a boolean argument. Defaults to "yes". If "no", causes the generator to ignore
           any mounts or swap devices configured in /etc/fstab.  rd.fstab= is honored only by the
           initial RAM disk (initrd) while fstab= is honored by both the main system and the
           initrd.

       root=
           Takes the root filesystem to mount in the initrd.  root= is honored by the initrd.

       rootfstype=
           Takes the root filesystem type that will be passed to the mount command.  rootfstype=
           is honored by the initrd.

       rootflags=
           Takes the root filesystem mount options to use.  rootflags= is honored by the initrd.

       mount.usr=
           Takes the /usr filesystem to be mounted by the initrd. If mount.usrfstype= or
           mount.usrflags= is set, then mount.usr= will default to the value set in root=.

           Otherwise, this parameter defaults to the /usr entry found in /etc/fstab on the root
           filesystem.

           mount.usr= is honored by the initrd.

       mount.usrfstype=
           Takes the /usr filesystem type that will be passed to the mount command. If mount.usr=
           or mount.usrflags= is set, then mount.usrfstype= will default to the value set in
           rootfstype=.

           Otherwise, this value will be read from the /usr entry in /etc/fstab on the root
           filesystem.

           mount.usrfstype= is honored by the initrd.

       mount.usrflags=
           Takes the /usr filesystem mount options to use. If mount.usr= or mount.usrfstype= is
           set, then mount.usrflags= will default to the value set in rootflags=.

           Otherwise, this value will be read from the /usr entry in /etc/fstab on the root
           filesystem.

           mount.usrflags= is honored by the initrd.

       systemd.volatile=
           Controls whether the system shall boot up in volatile mode. Takes a boolean argument
           or the special value state.

           If false (the default), this generator makes no changes to the mount tree and the
           system is booted up in normal mode.

           If true the generator ensures systemd-volatile-root.service(8) is run as part of the
           initial RAM disk ("initrd"). This service changes the mount table before transitioning
           to the host system, so that a volatile memory file system ("tmpfs") is used as root
           directory, with only /usr mounted into it from the configured root file system, in
           read-only mode. This way the system operates in fully stateless mode, with all
           configuration and state reset at boot and lost at shutdown, as /etc and /var will be
           served from the (initially unpopulated) volatile memory file system.

           If set to state the generator will leave the root directory mount point unaltered,
           however will mount a "tmpfs" file system to /var. In this mode the normal system
           configuration (i.e. the contents of "/etc") is in effect (and may be modified during
           system runtime), however the system state (i.e. the contents of "/var") is reset at
           boot and lost at shutdown.

           Note that in none of these modes the root directory, /etc, /var or any other resources
           stored in the root file system are physically removed. It's thus safe to boot a system
           that is normally operated in non-volatile mode temporarily into volatile mode, without
           losing data.

           Note that enabling this setting will only work correctly on operating systems that can
           boot up with only /usr mounted, and are able to automatically populate /etc, and also
           /var in case of "systemd.volatile=yes".

SEE ALSO

       systemd(1), fstab(5), systemd.mount(5), systemd.swap(5), systemd-cryptsetup-generator(8),
       kernel-command-line(7)