1FSTAB(5) Linux Programmer's Manual FSTAB(5)
2
6 fstab - static information about the filesystems
7
9 #include <fstab.h>
10
12 The file fstab contains descriptive information about the various file
13 systems. It is the duty of the system administrator to properly create
14 and maintain this file. fstab can be modified by special utils (e.g.
15 fstab-sync(8)). Each filesystem is described on a separate line;
16 fields on each line are separated by tabs or spaces. Lines starting
17 with '#' are comments. The order of records in fstab is important
18 because fsck(8), mount(8), and umount(8) sequentially iterate through
19 fstab doing their thing.
20 The first field, (fs_spec), describes the block special device or
22 remote filesystem to be mounted.
23 For ordinary mounts it will hold (a link to) a block special device
25 node (as created by mknod(8)) for the device to be mounted, like
26 `/dev/cdrom' or `/dev/sdb7'. For NFS mounts one will have
27 <host>:<dir>, e.g., `knuth.aeb.nl:/'. For procfs, use `proc'.
28 Instead of giving the device explicitly, one may indicate the (ext2 or
30 xfs) filesystem that is to be mounted by its UUID or volume label (cf.
31 e2label(8) or xfs_admin(8)), writing LABEL=<label> or UUID=<uuid>,
32 e.g., `LABEL=Boot' or `UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'.
33 This will make the system more robust: adding or removing a SCSI disk
34 changes the disk device name but not the filesystem volume label.
35 The second field, (fs_file), describes the mount point for the filesys‐
37 tem. For swap partitions, this field should be specified as `none'. If
38 the name of the mount point contains spaces these can be escaped as
39 `\040'.
40 The third field, (fs_vfstype), describes the type of the filesystem.
42 Linux supports lots of filesystem types, such as adfs, affs, autofs,
43 coda, coherent, cramfs, devpts, efs, ext2, ext3, hfs, hpfs, iso9660,
44 jfs, minix, msdos, ncpfs, nfs, ntfs, proc, qnx4, reiserfs, romfs,
45 smbfs, sysv, tmpfs, udf, ufs, umsdos, vfat, xenix, xfs, and possibly
46 others. For more details, see mount(8). For the filesystems currently
47 supported by the running kernel, see /proc/filesystems. An entry swap
48 denotes a file or partition to be used for swapping, cf. swapon(8). An
49 entry ignore causes the line to be ignored. This is useful to show
50 disk partitions which are currently unused.
51 The fourth field, (fs_mntops), describes the mount options associated
53 with the filesystem.
54 It is formatted as a comma separated list of options. It contains at
56 least the type of mount plus any additional options appropriate to the
57 filesystem type. For documentation on the available options for non-
58 nfs file systems, see mount(8). For documentation on all nfs-specific
59 options have a look at nfs(5). Common for all types of file system are
60 the options ``noauto'' (do not mount when "mount -a" is given, e.g., at
61 boot time), ``user'' (allow a user to mount), ``owner'' (allow device
62 owner to mount), ``pamconsole'' (allow a user at the console to mount),
63 and ``comment'' (e.g., for use by fstab-maintaining programs). The
64 ``owner'', ``pamconsole'' and ``comment'' options are Linux-specific.
65 For more details, see mount(8).
66 The fifth field, (fs_freq), is used for these filesystems by the
68 dump(8) command to determine which filesystems need to be dumped. If
69 the fifth field is not present, a value of zero is returned and dump
70 will assume that the filesystem does not need to be dumped.
71 The sixth field, (fs_passno), is used by the fsck(8) program to deter‐
73 mine the order in which filesystem checks are done at reboot time. The
74 root filesystem should be specified with a fs_passno of 1, and other
75 filesystems should have a fs_passno of 2. Filesystems within a drive
76 will be checked sequentially, but filesystems on different drives will
77 be checked at the same time to utilize parallelism available in the
78 hardware. If the sixth field is not present or zero, a value of zero
79 is returned and fsck will assume that the filesystem does not need to
80 be checked.
81 The proper way to read records from fstab is to use the routines getmn‐
83 tent(3).
84
86 /etc/fstab
87
89 getmntent(3), mount(8), swapon(8), fs(5) nfs(5) fstab-sync(8)
90
92 The ancestor of this fstab file format appeared in 4.0BSD.
93Linux 2.2 15 June 1999 FSTAB(5)