SYSTEMD-FSTAB-GENERATOR(8)             SYSTEMD-FSTAB-GENERATOR(8)

     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=

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     SYSTEMD-FSTAB-GENERATOR(8)             SYSTEMD-FSTAB-GENERATOR(8)

              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.

              Note that unlike most kernel command line options this
              setting does not override settings made in configuration
              files (specifically: the mount option string in
              /etc/fstab). See systemd-remount-fs.service(8).

          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

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              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.

              If this setting is set to "overlay" the root file system
              is set up as "overlayfs" mount combining the read-only
              root directory with a writable "tmpfs", so that no
              modifications are made to disk, but the file system may
              be modified nonetheless with all changes being lost at
              reboot.

              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 with the exception of "overlay" mode, 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".

          systemd.swap
              Takes a boolean argument or enables the option if
              specified without an argument. If disabled, causes the
              generator to ignore any swap devices configured in
              /etc/fstab. Defaults to enabled.

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

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