NAME

mntent − static information about filesystems

SYNOPSIS

#include <mntent.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, check consistency of, dump and restore file systems, and 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 of which would be:

/dev/xy0a / efs rw, 1 2

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;/* nfs, efs, bell, or ignore */
char*mnt_opts;/* ro, quota, etc. */
intmnt_freq;/* dump frequency, in days */
intmnt_passno;/* pass number on parallel fsck */
};

The fields are separated by white space, and 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.  Below is a list of the file system types currently supported and the way each of them interprets these fields. 

efs or bell

mnt_fsnameMust be a block special device. 

mnt_optsValid opts are ro, rw. 

nfs

mnt_fsnameThe path on the server of the directory to be served. 

mnt_optsValid opts are ro, rw, hard, soft. 

If the mnt_type is specified as “ignore” the entry is ignored.  This is useful to show disk partitions which are currently not used. 

mnt_freq and mnt_passno are not supported. 

/etc/fstab is only read by programs, and not written; it is the duty of the system administrator to properly create and maintain this file.  The order of records in /etc/fstab is important because mount and umount process the file sequentially; file systems must appear after file systems they are mounted within. 

FILES

/etc/fstab

SEE ALSO

fsck(1M), getmntent(3), mount(1M), umount(1M)

Version 2.5r1  —  October 29, 1986