fstab(4)
_________________________________________________________________
fstab File Format
static information about file systems
_________________________________________________________________
SYNTAX
#include <mnttab.h>
DESCRIPTION
The file /etc/fstab describes the file systems and swapping areas
used by the local machine. The system administrator can modify
it with a text editor. It is read by commands that mount, dump,
restore, and check the consistency of file systems, as well as by
the system in providing swap space. The file consists of a
number of lines like this:
fsname dir type opts freq passno
for example:
/dev/dsk/usr /usr dg/ux rw 1 1
would indicate a mount for a local file system, and
titan:/usr/titan /usr/titan nfs rw,hard 0 0
would indicate an NFS file system mount.
The fstab format was changed in order to support NFS file systems
as well as local file systems. The old-style fstab entries are
supported, but not recommended.
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; /* dg/ux, nfs, swap, or ignore */
char *mnt_opts; /* rw, ro, hard, soft */
int mnt_freq; /* highest dump level */
int mnt_passno; /* pass number on parallel fsck */
};
Fields are separated by white space; a #, as the first non-white
character, indicates a comment. The mnt_type field determines
how the mnt_fsname and mnt_opts fields will be interpreted. The
DG/UX 4.00 Page 1
Licensed material--property of copyright holder(s)
fstab(4)
following is a list of the file system types currently supported,
and the way each of them interprets these fields:
Type Field Interpretation
dg/ux mnt_fsname Must be a block special
device.
mnt_opts Valid options are ro, rw.
nfs mnt_fsname The hostname of the server and
the pathname on the server of
the directory to be served. A
colon separates the pathname
and hostname.
mnt_opts Valid options are ro, rw,
hard, soft.
swap mnt_fsname Must be a block special device
swap section.
mnt_opts Ignored.
If the mnt_type is specified as ignore then the entry is ignored.
This is useful to show disks not currently used.
Entries identified as swap are made available as swap space by
the swapon(1m) command at the end of the system reboot procedure.
When the mnt_fsname field is interpreted as a block special
device, programs that require the corresponding character special
device must construct the name by changing dsk to rdsk in the
pathname.
If the mnt_opts field is a comma-separated list of options that
includes ro or rw, then the file system is mounted read-write or
read-only. If this includes hard or soft, then the NFS file
system is mounted hard or soft.
The field mnt_freq indicates how often each file system should be
dumped by the dump(1m) command (and triggers that command's w
option, which determines what file systems should be dumped).
Most systems set the mnt_freq field to 1, indicating that file
systems are dumped each day.
The final field mnt_passno is used by the consistency checking
program fsck(1m) to allow overlapped checking of file systems
during a reboot. All file systems with a mnt_passno of 1 are
checked first simultaneously, then all file systems with
mnt_passno of 2 are checked, and so on. The <mnt_passno> of the
root file system should be 0, as the root cannot be checked since
it is already mounted.
Programs read the /etc/fstab file, but never write to it. It is
DG/UX 4.00 Page 2
Licensed material--property of copyright holder(s)
fstab(4)
the duty of the system administrator to maintain this file. The
order of records in /etc/fstab is important because fsck and
mount process the file sequentially; file systems must appear
after file systems they are mounted within. For example, if you
have an entry for /usr/spool, it must appear after the entry for
/usr.
FILES
/etc/fstab
SEE ALSO
getmntent(3), fsck(1m), mount(1m), getfsent(3x), swapon(1m),
dump(1m)
DG/UX 4.00 Page 3
Licensed material--property of copyright holder(s)