1SYSTEMD-FSTAB-GENERATOR(8)  systemd-fstab-generator SYSTEMD-FSTAB-GENERATOR(8)
2
3
4

NAME

6       systemd-fstab-generator - Unit generator for /etc/fstab
7

SYNOPSIS

9       /usr/lib/systemd/system-generators/systemd-fstab-generator
10

DESCRIPTION

12       systemd-fstab-generator is a generator that translates /etc/fstab (see
13       fstab(5) for details) into native systemd units early at boot and when
14       configuration of the system manager is reloaded. This will instantiate
15       mount and swap units as necessary.
16
17       The passno field is treated like a simple boolean, and the ordering
18       information is discarded. However, if the root file system is checked,
19       it is checked before all the other file systems.
20
21       See systemd.mount(5) and systemd.swap(5) for more information about
22       special /etc/fstab mount options this generator understands.
23
24       One special topic is handling of symbolic links. Historical init
25       implementations supported symlinks in /etc/fstab. Because mount units
26       will refuse mounts where the target is a symbolic link, this generator
27       will resolve any symlinks as far as possible when processing /etc/fstab
28       in order to enhance backwards compatibility. If a symlink target does
29       not exist at the time that this generator runs, it is assumed that the
30       symlink target is the final target of the mount.
31
32       systemd-fstab-generator implements systemd.generator(7).
33

KERNEL COMMAND LINE

35       systemd-fstab-generator understands the following kernel command line
36       parameters:
37
38       fstab=, rd.fstab=
39           Takes a boolean argument. Defaults to "yes". If "no", causes the
40           generator to ignore any mounts or swap devices configured in
41           /etc/fstab.  rd.fstab= is honored only by the initial RAM disk
42           (initrd) while fstab= is honored by both the main system and the
43           initrd.
44
45       root=
46           Takes the root filesystem to mount in the initrd.  root= is honored
47           by the initrd.
48
49       rootfstype=
50           Takes the root filesystem type that will be passed to the mount
51           command.  rootfstype= is honored by the initrd.
52
53       rootflags=
54           Takes the root filesystem mount options to use.  rootflags= is
55           honored by the initrd.
56
57           Note that unlike most kernel command line options this setting does
58           not override settings made in configuration files (specifically:
59           the mount option string in /etc/fstab). See systemd-remount-
60           fs.service(8).
61
62       mount.usr=
63           Takes the /usr filesystem to be mounted by the initrd. If
64           mount.usrfstype= or mount.usrflags= is set, then mount.usr= will
65           default to the value set in root=.
66
67           Otherwise, this parameter defaults to the /usr entry found in
68           /etc/fstab on the root filesystem.
69
70           mount.usr= is honored by the initrd.
71
72       mount.usrfstype=
73           Takes the /usr filesystem type that will be passed to the mount
74           command. If mount.usr= or mount.usrflags= is set, then
75           mount.usrfstype= will default to the value set in rootfstype=.
76
77           Otherwise, this value will be read from the /usr entry in
78           /etc/fstab on the root filesystem.
79
80           mount.usrfstype= is honored by the initrd.
81
82       mount.usrflags=
83           Takes the /usr filesystem mount options to use. If mount.usr= or
84           mount.usrfstype= is set, then mount.usrflags= will default to the
85           value set in rootflags=.
86
87           Otherwise, this value will be read from the /usr entry in
88           /etc/fstab on the root filesystem.
89
90           mount.usrflags= is honored by the initrd.
91
92       systemd.volatile=
93           Controls whether the system shall boot up in volatile mode. Takes a
94           boolean argument or the special value state.
95
96           If false (the default), this generator makes no changes to the
97           mount tree and the system is booted up in normal mode.
98
99           If true the generator ensures systemd-volatile-root.service(8) is
100           run as part of the initial RAM disk ("initrd"). This service
101           changes the mount table before transitioning to the host system, so
102           that a volatile memory file system ("tmpfs") is used as root
103           directory, with only /usr mounted into it from the configured root
104           file system, in read-only mode. This way the system operates in
105           fully stateless mode, with all configuration and state reset at
106           boot and lost at shutdown, as /etc and /var will be served from the
107           (initially unpopulated) volatile memory file system.
108
109           If set to state the generator will leave the root directory mount
110           point unaltered, however will mount a "tmpfs" file system to /var.
111           In this mode the normal system configuration (i.e. the contents of
112           "/etc") is in effect (and may be modified during system runtime),
113           however the system state (i.e. the contents of "/var") is reset at
114           boot and lost at shutdown.
115
116           If this setting is set to "overlay" the root file system is set up
117           as "overlayfs" mount combining the read-only root directory with a
118           writable "tmpfs", so that no modifications are made to disk, but
119           the file system may be modified nonetheless with all changes being
120           lost at reboot.
121
122           Note that in none of these modes the root directory, /etc, /var or
123           any other resources stored in the root file system are physically
124           removed. It's thus safe to boot a system that is normally operated
125           in non-volatile mode temporarily into volatile mode, without losing
126           data.
127
128           Note that with the exception of "overlay" mode, enabling this
129           setting will only work correctly on operating systems that can boot
130           up with only /usr mounted, and are able to automatically populate
131           /etc, and also /var in case of "systemd.volatile=yes".
132

SEE ALSO

134       systemd(1), fstab(5), systemd.mount(5), systemd.swap(5), systemd-
135       cryptsetup-generator(8), kernel-command-line(7)
136
137
138
139systemd 245                                         SYSTEMD-FSTAB-GENERATOR(8)
Impressum