fstab(5) File Formats Manual fstab(5)
fstab - file containing static information about known file systems
The file contains descriptive information about the known file systems. By convention, is created and maintained as a read-only file by
the system administrator. Each file system is described by its own line within The order of these lines and the file systems they repre-
sent is important because and sequentially process in the performance of their tasks.
The format of each file system description in is as follows:
The meanings of these fields are:
spec The block special file name of the device on which the file system is located. It can also be a network name for such as or
file The pathname of the directory on which the file system is mounted.
type How 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
freq The frequency (in days) with which the command dumps the rw, ro, and rq file systems.
passno The order in which the command checks the rw, ro, and rq file systems at reboot time.
name The name of the file system type. File systems can have the following types: ufs -- ULTRIX file system and nfs -- SUN Network
options The 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 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 command and disk quotas are automatically processed by the command and then enabled by the command for rq file systems.
Here is a sample file:
The last three entries in the sample shown use NFS options as described in the reference page.
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
All field delimiters (:) must exist within each file system description; 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 should be parsed only through use of the routines.
File system information file
getfsent(3x), dump(8), fsck(8), mount(8), mount(8nfs), mount(8ufs) quotacheck(8), quotaon(8), swapon(8)