SYSTEMD-FSTAB-GENERATOR(8) | systemd-fstab-generator | SYSTEMD-FSTAB-GENERATOR(8) |
NAME
systemd-fstab-generator - Unit generator for /etc/fstabSYNOPSIS
/usr/lib/systemd/system-generators/systemd-fstab-generatorDESCRIPTION
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)systemd 238 |