fstab(4)                                                 fstab(4)



     NAME
          fstab - static information about file systems

     SYNOPSIS
          #include <mntent.h>

     DESCRIPTION
          The file /etc/fstab describes the file systems and swapping
          partitions used by the local machine.  It can be modified
          with a text editor by the system administrator.  The file is
          read by commands that mount, unmount, and check the con-
          sistency of file systems; it is also read by the system in
          providing swap space.  Because there is an appropriate mount
          request in the /etc/rc startup file, any file systems
          described in /etc/fstab (other than those of type ignore or
          with mount option noauto) are mounted automatically whenever
          multi-user mode is entered.

          The /etc/fstab file consists of a number of lines in the
          following format

               fsname dir type opts freq passno

          For example

             /dev/xy0a / 5.2 rw,noquota 1 2


          The field freq is optionally used by dump.bsd(1M) to help
          report which file systems need to be dumped.  passno is used
          by fsck(1M) to help select which file systems to check.  For
          example, fsck -p2 checks all the 5.2 file systems listed in
          /etc/fstab with passno greater than or equal to 2.

          The entries from this file are accessed using the routines
          in getmntent(3), which returns a structure of the following
          form:

          struct mntent {
              char    *mnt_fsname; /* file system name */
              char    *mnt_dir;    /* file system path prefix */
              char    *mnt_type;   /* 4.2, 5.2, nfs, swap,
                                      or ignore */
              char    *mnt_opts;   /* rw, ro, noquota, quota, noauto,
                                      hard, soft */
              int     mnt_freq;    /* dump frequency, in days */
              int     mnt_passno;  /* pass # on parallel fsck */
          };


          Fields are separated by white space; a # as the first
          nonwhite character indicates a comment.



     April, 1990                                                     1

     fstab(4)                                                 fstab(4)



          The mnt_type field determines how the mnt_fsname and
          mnt_opts fields will be interpreted.  Here is a list of the
          file system types currently supported, and the way each of
          them interprets these fields.

        4.2/5.2
          mnt_fsname          Must be a block device.

          mnt_opts            Valid options are ro, rw, quota, noquo-
                              ta, noauto.

        NFS
          mnt_fsname          The path on the server of the directory
                              to be served.

          mnt_opts            Valid options are ro, rw, quota, noquo-
                              ta, noauto, hard, soft.

        SWAP
          mnt_fsname          Must be a block device swap partition.

          mnt_opts            Ignored.

          If the mnt_opts field contains noauto, the entry will be ig-
          nored during a mount -a command, allowing definition of
          fstab entries for commonly used file systems not mounted au-
          tomatically.

          If the mnt_type is specified as ignore then the entry is ig-
          nored.  This is useful to show disk partitions not currently
          used.

          The /etc/fstab file is only read by programs and never writ-
          ten by them; it is the duty of the system administrator to
          maintain this file.  The order of records in /etc/fstab is
          important because fsck, mount, and umount process the file
          sequentially; file systems must appear following the file
          systems they are mounted in.

          Note that listing a file system as type swap will not cause
          the system to mount the file system as a swap area; to do
          that, you must use the swap command.

     FILES
          /etc/fstab

     SEE ALSO
          dump.bsd(4), fsck(1M), mount(1M), swap(1M), getmntent(3).







     2                                                     April, 1990