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- stretch 232-25+deb9u11
- testing 241-5
- stretch-backports 241-3~bpo9+1
- unstable 241-5
- experimental 242-2
SYSTEMD-FSTAB-GENERATOR(8) | systemd-fstab-generator | SYSTEMD-FSTAB-GENERATOR(8) |
NAME¶
systemd-fstab-generator - Unit generator for /etc/fstabSYNOPSIS¶
/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=
root=
rootfstype=
rootflags=
mount.usr=
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=
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=
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=
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 241 |