NAME

fstab, mtab − static filesystem mounting table, mounted filesystems table

SYNOPSIS

/etc/fstab

/etc/mtab

DESCRIPTION

The /etc/fstab file contains entries for filesystems and disk partitions to mount using the mount(8) command, which is normally invoked by the rc.boot script at boot time.  This file is used by various utilities that mount, unmount, check the consistency of, dump, and restore file systems.  It is also used by the system itself when locating the swap partition. 

The /etc/mtab file contains entries for filesystems currently mounted, and is read by programs using the routines described in getmntent(3).  umount (see mount(8)) removes entries from this file. 

Each entry consists of a line of the form:

filesystem   directory   type   options   freq   pass

filesystem is the pathname of a block-special device, or the name of a remote filesystem in host:pathname form. 

directory is the pathname of the directory on which to mount the filesystem. 

type is the filesystem type, which can be one of:

4.2 to mount a block-special device

lo to loopback-mount a file system

nfs to mount an exported NFS filesystem

swap to indicate a swap partition

ignore to have the mount command ignore the current entry (good for noting disk partitions that are not being used)

options contains a comma-separated list (no spaces) of mounting options, some of which can be applied to all types of filesystems, and others which only apply to specific types. 

4.2 options:

quota|noquota
disk quotas are enforced or not enforced

nfs options:

bg|fg If the first attempt fails, retry in the background, or, in the foreground

retry=n The number of times to retry the mount operation. 

rsize=n Set the read buffer size to n bytes. 

wsize=n Set the write buffer size to n bytes. 

timeo=n Set the NFS timeout to n tenths of a second. 

retrans=n The number of NFS retransmissions. 

port=n The server IP port number. 

soft|hard Return an error if the server does not respond, or continue the retry request until the server responds. 

intr Allow keyboard interrupts on hard mounts. 

secure Use a more secure protocol for NFS transactions. 

acregmin=n Hold cached attributes for at least n seconds after file modification. 

acregmax=n Hold cached attributes for no more than n seconds after file modification. 

acdirmin=n Hold cached attributes for at least n seconds after directory update. 

acdirmax=n Hold cached attributes for no more than n seconds after directory update. 

actimeo=n Set min and max times for regular files and directories to n seconds. 

Common options:

ro|rw mount either read-only or read-write

suid|nosuid
setuid execution allowed or disallowed

grpid Create files with BSD semantics for propagation of the group ID.  With this option, files inherit the group ID of the directory in which they are created, regardless of the directory’s setgid bit. 

noauto Do not mount this file system automatically (using mount −a). 

freq is the interval (in days) between dumps. 

pass is the fsck(8) pass in which to check the partition.  Filesystems with the same pass number are checked simultaneously.  Filesystems with pass equal to 0 are not checked. 

A pound-sign (#) as the first non-white character indicates a comment line which is ignored by routines that read this file.  The order of records in /etc/fstab is important because fsck, mount, and umount process the file sequentially; an entry for a file system must appear after the entry for any file system it is to be mounted on top of. 

EXAMPLES

In this example, two partitions on the local disk are 4.2 mounted.  Several directories are loopback mounted to appear in the traditional file system locations on the local system.  The /home/user directory is hard mounted read-write over the NFS (the automounter is not in use here), along with  additional swap space in the form of a mounted swap file (see System and Network Administration for details on adding swap space):

/dev/xy0a / 4.2 rw,noquota 1 1
/dev/xy0b /usr 4.2 rw,noquota 1 1
/export/tmp/localhost /tmp lo rw 0 0
/export/var/localhost /var lo rw 0 0
example:/home/user /home/user nfs rw,hard,fg 0 0
/export/swap/myswap swap swap rw 0 0

The following example /etc/fstab entries apply to the Sun386i:

/dev/sd0a / 4.2 rw,noquota 1 1
/dev/sd0g /usr 4.2 ro 1 2
/export/cluster/sun386.sunos4.0.1 /usr/cluster lo rw 0 0
/export/local/sun386 /usr/local lo rw 0 0

FILES

/etc/fstab

/etc/mtab

SEE ALSO

mount(2), getmntent(3), lofs(4S), fstab(5), automount(8), fsck(8), mount(8), quotacheck(8), quotaon(8) System and Network Administration

BUGS

Correct caching of NFS data currently relies on server and client clocks being close (within a few seconds of each other). 

Sun Release 4.0  —  Last change: 17 July 1989