FSTAB(5) —
NAME
fstab − static information about the filesystems (includes NFS extensions)
SYNOPSIS
#include <fstab.h>
DESCRIPTION
The file /etc/fstab describes the file systems and swapping partitions used by the local machine. It is created by the system administrator using a text editor and processed by commands which mount, unmount, dump, restore and check the consistency of file systems. It is also processed by the system in providing swap space.
It consists of a number of lines of the form:
fsname dir type opts freq passno
An example would be (See mntent(5) for full structure):
/dev/hd0a / ufs rw,noquota 1 2
#defineFSTAB_RW"rw"/∗ read-write device ∗/
#defineFSTAB_RO"ro"/∗ read-only device ∗/
#defineFSTAB_RQ"rq"/∗ read-write with quotas ∗/
#defineFSTAB_SW"sw"/∗ swap device ∗/
#defineFSTAB_XX"xx"/∗ ignore totally ∗/
struct fstab {
char∗fs_spec;/∗ block special device name ∗/
char∗fs_file;/∗ file system path prefix ∗/
char∗fs_type;/∗ rw,ro,sw or xx ∗/
intfs_freq;/∗ dump frequency, in days ∗/
intfs_passno;/∗ pass number on parallel dump ∗/
};
The special file name is the block special file name, and not the character special file name. If a program needs the character special file name, the program must create it by appending a “r” after the last “/” in the special file name.
If fs_type is “rw” or “ro” then the file system whose name is given in the fs_file field is normally mounted read-write or read-only on the specified special file. If fs_type is “rq”, then the file system is normally mounted read-write with disk quotas enabled. The fs_freq field is used for these file systems by the dump(8) command to determine which file systems need to be dumped. The fs_passno field is used by the fsck(8) program to determine the order in which file system checks are done at reboot time. The root file system should be specified with a fs_passno of 1, and other file systems should have larger numbers. File systems within a drive should have distinct numbers, but file systems on different drives can be checked on the same pass to utilize parallelism available in the hardware.
If fs_type is “sw” then the special file is made available as a piece of swap space by the swapon(8) command at the end of the system reboot procedure. The fields other than fs_spec and fs_type are not used in this case.
If fs_type is “rq” then at boot time the file system is automatically processed by the quotacheck(8) command and disk quotas are then enabled with quotaon(8). File system quotas are maintained in a file “quotas”, which is located at the root of the associated file system.
If fs_type is specified as “xx” the entry is ignored. This is useful to show disk partitions which are currently not used.
The proper way to read records from /etc/fstab is to use the routines getfsent(), getfsspec(), getfstype(), and getfsfile().
FILES
/etc/fstab
SEE ALSO
PRPQs 5799-WZQ/5799-PFF: IBM/4.3 — Sept 1988