mount/fstab.5

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  32 .\"     @(#)fstab.5     6.5 (Berkeley) 5/10/91
  33 .\"
  34 .\" Modified Sat Mar  6 20:45:03 1993, faith@cs.unc.edu, for Linux
  35 .\" Sat Oct  9 10:07:10 1993: converted to man format by faith@cs.unc.edu
  36 .\" Sat Nov 20 20:47:38 1993: hpfs documentation added
  37 .\" Sat Nov 27 20:23:32 1993: Updated authorship information
  38 .\" Wed Jul 26 00:00:00 1995: Updated some nfs stuff, joey@infodrom.north.de
  39 .\" Tue Apr  2 00:38:28 1996: added info about "noauto", "user", etc.
  40 .\" Tue Jun 15 20:02:18 1999: added LABEL and UUID
  41 .\"
  42 .TH FSTAB 5 "15 June 1999" "Linux 2.2" "Linux Programmer's Manual"
  43 .SH NAME
  44 fstab \- static information about the filesystems
  45 .SH SYNOPSIS
  46 .B #include <fstab.h>
  47 .SH DESCRIPTION
  48 The file
  49 .B fstab
  50 contains descriptive information about the various file systems.
  51 .B fstab
  52 is only read by programs, and not written; it is the duty of the system
  53 administrator to properly create and maintain this file.  Each filesystem
  54 is described on a separate line; fields on each line are separated by tabs
  55 or spaces.  Lines starting with '#' are comments.  The order of records in
  56 .B fstab
  57 is important because
  58 .BR fsck (8),
  59 .BR mount (8),
  60 and
  61 .BR umount (8)
  62 sequentially iterate through
  63 .B fstab
  64 doing their thing.
  65
  66 The first field,
  67 .RI ( fs_spec ),
  68 describes the block special device or
  69 remote filesystem to be mounted.
  70 .LP
  71 For ordinary mounts it will hold (a link to) a block special
  72 device node (as created by
  73 .BR mknod (8))
  74 for the device to be mounted, like `/dev/cdrom' or `/dev/sdb7'.
  75 For NFS mounts one will have <host>:<dir>, e.g., `knuth.aeb.nl:/'.
  76 For procfs, use `proc'.
  77 .LP
  78 Instead of giving the device explicitly, one may indicate
  79 the (ext2 or xfs) filesystem that is to be mounted by its UUID or
  80 volume label (cf.
  81 .BR e2label (8)
  82 or
  83 .BR xfs_admin (8)),
  84 writing LABEL=<label> or UUID=<uuid>,
  85 e.g., `LABEL=Boot' or `UUID=3e6be9de\%-8139\%-11d1\%-9106\%-a43f08d823a6'.
  86 This will make the system more robust: adding or removing a SCSI disk
  87 changes the disk device name but not the filesystem volume label.
  88
  89 The second field,
  90 .RI ( fs_file ),
  91 describes the mount point for the filesystem.  For swap partitions, this
  92 field should be specified as `none'. If the name of the mount point
  93 contains spaces these can be escaped as `\\040'.
  94
  95 The third field,
  96 .RI ( fs_vfstype ),
  97 describes the type of the filesystem.  Linux supports lots
  98 of filesystem types, such as
  99 .IR adfs ,
 100 .IR affs ,
 101 .IR autofs ,
 102 .IR coda ,
 103 .IR coherent ,
 104 .IR cramfs ,
 105 .IR devpts ,
 106 .IR efs ,
 107 .IR ext2 ,
 108 .IR ext3 ,
 109 .IR hfs ,
 110 .IR hpfs ,
 111 .IR iso9660 ,
 112 .IR jfs ,
 113 .IR minix ,
 114 .IR msdos ,
 115 .IR ncpfs ,
 116 .IR nfs ,
 117 .IR ntfs ,
 118 .IR proc ,
 119 .IR qnx4 ,
 120 .IR reiserfs ,
 121 .IR romfs ,
 122 .IR smbfs ,
 123 .IR sysv ,
 124 .IR tmpfs ,
 125 .IR udf ,
 126 .IR ufs ,
 127 .IR umsdos ,
 128 .IR vfat ,
 129 .IR xenix ,
 130 .IR xfs ,
 131 and possibly others. For more details, see
 132 .BR mount (8).
 133 For the filesystems currently supported by the running kernel, see
 134 .IR /proc/filesystems .
 135 An entry
 136 .I swap
 137 denotes a file or partition to be used
 138 for swapping, cf.\&
 139 .BR swapon (8).
 140 An entry
 141 .I ignore
 142 causes the line to be ignored.  This is useful
 143 to show disk partitions which are currently unused.
 144
 145 The fourth field,
 146 .RI ( fs_mntops ),
 147 describes the mount options associated with the filesystem.
 148
 149 It is formatted as a comma separated list of options.  It contains at least
 150 the type of mount plus any additional options appropriate to the filesystem
 151 type.  For documentation on the available options for non-nfs file systems,
 152 see
 153 .BR mount (8).
 154 For documentation on all nfs-specific options have a look at
 155 .BR nfs (5).
 156 Common for all types of file system are the options ``noauto''
 157 (do not mount when "mount -a" is given, e.g., at boot time), ``user''
 158 (allow a user to mount), and ``owner''
 159 (allow device owner to mount). For more details, see
 160 .BR mount (8).
 161
 162 The fifth field,
 163 .RI ( fs_freq ),
 164 is used for these filesystems by the
 165 .BR dump (8)
 166 command to determine which filesystems need to be dumped.  If the fifth
 167 field is not present, a value of zero is returned and
 168 .B dump
 169 will assume that the filesystem does not need to be dumped.
 170
 171 The sixth field,
 172 .RI ( fs_passno ),
 173 is used by the
 174 .BR fsck (8)
 175 program to determine the order in which filesystem checks are done at
 176 reboot time.  The root filesystem should be specified with a
 177 .I fs_passno
 178 of 1, and other filesystems should have a
 179 .I fs_passno
 180 of 2.  Filesystems within a drive will be checked sequentially, but
 181 filesystems on different drives will be checked at the same time to utilize
 182 parallelism available in the hardware.  If the sixth field is not present
 183 or zero, a value of zero is returned and
 184 .B fsck
 185 will assume that the filesystem does not need to be checked.
 186
 187 The proper way to read records from
 188 .B fstab
 189 is to use the routines
 190 .BR getmntent (3).
 191 .SH FILES
 192 .I /etc/fstab
 193 .SH "SEE ALSO"
 194 .BR getmntent (3),
 195 .BR mount (8),
 196 .BR swapon (8),
 197 .BR fs (5)
 198 .BR nfs (5)
 199 .SH HISTORY
 200 The ancestor of this
 201 .B fstab
 202 file format appeared in 4.0BSD.
 203 .\" But without comment convention, and options and vfs_type.
 204 .\" Instead there was a type rw/ro/rq/sw/xx, where xx is the present 'ignore'.