1FSTAB(5) File Formats 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. fstab is only read by programs, and not written; it is the
14 duty of the system administrator to properly create and maintain this
15 file. Each filesystem is described on a separate line; fields on each
16 line are separated by tabs or spaces. The order of records in fstab is
17 important because fsck(8), mount(8), and umount(8) sequentially iterate
18 through fstab doing their thing.
19 The first field, fs_spec, describes the block special device or remote
21 filesystem to be mounted. For filesystems of type ufs, the special
22 file name is the block special file name, and not the character special
23 file name. If a program needs the character special file name, the
24 program must create it by appending a ``r'' after the last ``/'' in the
25 special file name.
26 The second field, fs_file, describes the mount point for the filesys‐
28 tem. For swap partitions, this field should be specified as ``none''.
29 The third field, fs_vfstype, describes the type of the filesystem. The
31 system currently supports only two types of filesystems:
32 ufs a local UNIX filesystem
34 swap a disk partition to be used for swapping
36 The fourth field, fs_mntops, describes the mount options associated
38 with the filesystem. It is formatted as a comma separated list of
39 options. It contains at least the type of mount (see fs_type below)
40 plus any additional options appropriate to the filesystem type.
41 If the option ``quotas'' is specified, the filesystem is automatically
43 processed by the quotacheck(8) command, and user disk quotas are
44 enabled with quotaon(8). Filesystem quotas are maintained in the file
45 named quotas located at the root of the associated filesystem. This
46 restriction on the location of the quotas file is needlessly imposed by
47 the kernel but may be lifted in the future. Thus, if the user quota
48 file for /tmp is stored in /var/quotas/tmp.user, this location can be
49 specified as:
50 quotas=/var/quotas/tmp.user
52 The type of the mount is extracted from the fs_mntops field and stored
54 separately in the fs_type field (it is not deleted from the fs_mntops
55 field). If fs_type is ``rw'' or ``ro'' then the filesystem whose name
56 is given in the fs_file field is normally mounted read-write or read-
57 only on the specified special file. If fs_type is ``sw'' then the spe‐
58 cial file is made available as a piece of swap space by the swapon(8)
59 command at the end of the system reboot procedure. The fields other
60 than fs_spec and fs_type are unused. If fs_type is specified as ``xx''
61 the entry is ignored. This is useful to show disk partitions which are
62 currently unused.
63 The fifth field, fs_freq, is used for these filesystems by the dump(8)
65 command to determine which filesystems need to be dumped. If the fifth
66 field is not present, a value of zero is returned and dump(8) will
67 assume that the filesystem does not need to be dumped.
68 The sixth field, fs_passno, is used by the fsck(8) program to determine
70 the order in which filesystem checks are done at reboot time. The root
71 filesystem should be specified with a fs_passno of 1, and other
72 filesystems should have a fs_passno of 2. Filesystems within a drive
73 will be checked sequentially, but filesystems on different drives will
74 be checked at the same time to utilize parallelism available in the
75 hardware. If the sixth field is not present or zero, a value of zero
76 is returned and fsck(8) will assume that the filesystem does not need
77 to be checked.
78 #define FSTAB_RW "rw" /* read-write device */
80 #define FSTAB_RO "ro" /* read-only device */
81 #define FSTAB_SW "sw" /* swap device */
82 #define FSTAB_XX "xx" /* ignore totally */
83 struct fstab {
85 char *fs_spec; /* block special device name */
86 char *fs_file; /* filesystem path prefix */
87 char *fs_vfstype; /* type of filesystem */
88 char *fs_mntops; /* comma separated mount options */
89 char *fs_type; /* rw, ro, sw, or xx */
90 int fs_freq; /* dump frequency, in days */
91 int fs_passno; /* pass number on parallel dump */
92 };
93 The proper way to read records from fstab is to use the routines getf‐
95 sent(3), getfsspec(3), getfstype(3), and getfsfile(3).
96
98 /etc/fstab The file fstab resides in /etc.
99
101 getfsent(3)
102
104 The fstab file format appeared in 4.0BSD.
1054.4 Berkeley Distribution January 15, 1996 FSTAB(5)