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NetBSD 6.1.5 - man page for fstab (netbsd section 5)

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FSTAB(5)			     BSD File Formats Manual				 FSTAB(5)

NAME
     fstab -- file system table for devices, types, and mount points

SYNOPSIS
     #include <fstab.h>

DESCRIPTION
     The file fstab contains descriptive information about the various file systems.  fstab is
     only read by programs, and not written; it is the duty of the system administrator to prop-
     erly create and maintain this file.  Each file system is described on a separate line;
     fields on each line are separated by tabs or spaces.  Lines beginning with ``#'' are com-
     ments.  The order of records in fstab is important because fsck(8), mount(8), and umount(8)
     sequentially iterate through fstab doing their respective tasks.

     Each configuration line/record in fstab has the format:
	   fs_spec fs_file fs_vfstype fs_mntops fs_freq fs_passno

     The first field, (fs_spec), describes the block special device or remote file system to be
     mounted.  For file systems of type ffs, the special file name is the block special file
     name, and not the character special file name.  If a program needs the character special
     file name, the program must create it by appending a ``r'' after the last ``/'' in the spe-
     cial file name.

     The second field, (fs_file), describes the mount point for the file system.  For swap and
     dump partitions, this field should be specified as ``none''.

     The third field, (fs_vfstype), describes the type of the file system.  The system currently
     supports these file systems:

	   adosfs    an AmigaDOS file system.

	   cd9660    an ISO 9660 CD-ROM file system.

	   ext2fs    an implementation of the Linux ``Second Extended File-system''.

	   fdesc     an implementation of /dev/fd.

	   ffs	     a local UNIX file system.

	   filecore  a file system for RISC OS.

	   kernfs    various and sundry kernel statistics.

	   lfs	     a log-structured file-system.

	   mfs	     a local memory-based UNIX file system.

	   msdos     an MS-DOS ``FAT file system''.

	   nfs	     a Sun Microsystems compatible ``Network File System''.

	   ntfs      a file system used by Windows NT.	Still experimental.

	   null      a loop-back file system, allowing parts of the system to be viewed else-
		     where.

	   overlay   a demonstration of layered file systems.

	   portal    a general file system interface, currently supports TCP and FS mounts.

	   procfs    a local file system of process information.

	   ptyfs     a pseudo-terminal device file system.

	   smbfs     a shared resource from an SMB/CIFS file server.

	   swap      a disk partition to be used for swapping and paging.

	   tmpfs     an efficient memory file system.

	   umap      a user and group re-mapping file system.

	   union     a translucent file system.

     The fourth field, (fs_mntops), describes the mount options associated with the file system.
     It is formatted as a comma separated list of options.  It contains at least the type of
     mount (see fs_type below) plus any additional options appropriate to the file system type.

     The option ``auto'' can be used in the ``noauto'' form to cause a file system not to be
     mounted automatically (with ``mount -a'' , or system boot time).

     If the options ``userquota'' and/or ``groupquota'' are specified, the file system is auto-
     matically processed by the quotacheck(8) command, and legacy user and/or group disk quotas
     are enabled with quotaon(8).  By default, file system quotas are maintained in files named
     quota.user and quota.group which are located at the root of the associated file system.
     These defaults may be overridden by putting an equal sign and an alternative absolute path-
     name following the quota option.  Thus, if the user quota file for /tmp is stored in
     /var/quotas/tmp.user, this location can be specified as:

	   userquota=/var/quotas/tmp.user

     It is recommended to turn on the new, in-file system quota with tunefs(8) or at newfs(8)
     time, and to not use the ``userquota'' or ``groupquota'' options.	Migration of limits to
     the new in-file system quota can be handled via quotadump(8) and quotarestore(8).

     The option ``rump'' is used to mount the file system using a rump(3) userspace server
     instead of the kernel server.

     The type of the mount is extracted from the fs_mntops field and stored separately in the
     fs_type field (it is not deleted from the fs_mntops field).  If fs_type is ``rw'' or ``ro''
     then the file system whose name is given in the fs_file field is normally mounted read-write
     or read-only on the specified special file.  If fs_type is ``sw'' or ``dp'' then the special
     file is made available as a piece of swap or dump space by the swapctl(8) command towards
     the beginning of the system reboot procedure.  See swapctl(8) for more information on con-
     figuring swap and dump devices.  The fields other than fs_spec and fs_type are unused.  If
     fs_type is specified as ``xx'' the entry is ignored.  This is useful to show disk partitions
     which are currently unused.

     The fifth field, (fs_freq), is used for these file systems by the dump(8) command to deter-
     mine which file systems need to be dumped.  If the fifth field is not present, a value of
     zero is returned and dump(8) will assume that the file system does not need to be dumped.

     The sixth field, (fs_passno), is used by the fsck(8) program to determine the order in which
     file system checks are done at reboot time.  The root file system should be specified with a
     fs_passno of 1, and other file systems should have a fs_passno of 2.  Filesystems within a
     drive will be checked sequentially, but file systems on different drives will be checked at
     the same time to use parallelism available in the hardware.  If the sixth field is not
     present or zero, a value of zero is returned and fsck(8) will assume that the file system
     does not need to be checked.

     #define FSTAB_RW	     "rw"    /* read-write device */
     #define FSTAB_RQ	     "rq"    /* read/write with quotas */
     #define FSTAB_RO	     "ro"    /* read-only device */
     #define FSTAB_SW	     "sw"    /* swap device */
     #define FSTAB_DP	     "dp"    /* dump device */
     #define FSTAB_XX	     "xx"    /* ignore totally */

     struct fstab {
	     char    *fs_spec;	     /* block special device name */
	     char    *fs_file;	     /* file system path prefix */
	     char    *fs_vfstype;    /* type of file system */
	     char    *fs_mntops;     /* comma separated mount options */
	     char    *fs_type;	     /* rw, ro, sw, or xx */
	     int     fs_freq;	     /* dump frequency, in days */
	     int     fs_passno;      /* pass number on parallel fsck */
     };

     The proper way to read records from fstab is to use the routines getfsent(3), getfsspec(3),
     and getfsfile(3).

FILES
     /etc/fstab  The location of fstab configuration file.

     /usr/share/examples/fstab/
		 Some useful configuration examples.

SEE ALSO
     getfsent(3), mount(8), swapctl(8)

HISTORY
     The fstab file format appeared in 4.0BSD.

BSD					  March 6, 2011 				      BSD
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