fstab(5)

NAME

fstab − file containing static information about known file systems

DESCRIPTION

The /etc/fstab file contains descriptive information about the known file systems. By convention, /etc/fstab is created and maintained as a read-only file by the system administrator. Each file system is described by its own line within /etc/fstab. The order of these lines and the file systems they represent is important because fsck and mount sequentially process /etc/fstab in the performance of their tasks.

The format of each file system description in /etc/fstab is as follows:

spec:file:type:freq:passno:name:options

The meanings of these fields are:

specThe block special file name of the device on which the file system is located. It can also be a network name for nfs, such as /@erie or /@suez.

fileThe pathname of the directory on which the file system is mounted.

typeHow the file system is mounted. The ways in which a file system can be mounted are
rw - mount the file system read-write
ro - mount the file system read only
rq - mount the file system read-write with quotas
sw - make the special file part of the swap space
xx - ignore the entry

freqThe frequency (in days) with which the dump command dumps the rw, ro, and rq file systems.

passnoThe order in which the fsck command checks the rw, ro, and rq file systems at reboot time.

nameThe name of the file system type. File systems can have the following types: ufs - ULTRIX file system
nfs - SUN Network file system

optionsThe options field. This field contains an arbitrary string meaningful only when mounting file systems with the specified file system type name, such as NFS. The specific options are described in the mount reference pages.

Special actions occur for file systems of type sw and rq at system boot time. File systems of type sw are made part of the swap space by the swapon() command and disk quotas are automatically processed by the quotacheck() command and then enabled by the quotaon() command for rq file systems.

EXAMPLE

Here is a sample fstab file:

/dev/ra0a:/:rw:1:1:ufs::
/dev/ra1g:/usr:rw:1:2:ufs::
/@bigvax:/bigvax:rw:0:0:nfs::
/usr/uws2.0@bigvax:/usr/uws2.0:rw:0:0:nfs:soft,bg,nosuid:
/usr/dec@bigvax:/usr/dec:rw:0:0:nfs:bg,soft,nosuid:
/usr/pro/xyz@vax:/usr/pro/xyz:rw:0:0:nfs:bg,soft,intr,nosuid:

The last three entries in the fstab sample shown use NFS options as described in the mount() reference page.

RESTRICTIONS

The passno field of the root file system should be specified as 1. Other file systems should have larger values. File systems on the same device should have distinct passno fields. File systems on different devices may have the identical passno fields to allow them to be simultaneously checked.

All field delimiters (:) must exist within each file system description and only the options field may not be present. However, only the fields spec and type are meaningful to sw file systems and only the type field is meaningful to xx file systems.

The file system description within /etc/fstab should be parsed only through use of the getfsent routines.

FILES

/etc/fstab File system information file

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