AUTOFS(5)

NAME
autofs - Format of the automounter maps

DESCRIPTION
The automounter maps are files or NIS maps referred to by the master map of the automounter (see auto.master(5)). The automounter maps describe how file systems below the mountpoint of the map (given in the auto.master file) are to be mounted. This describes the sun map format; if another map format is specified (e.g. hesiod), this documentation does not apply. Maps can be changed on the fly and the automouter will recognize those changes on the next operation it performs on that map. This is not true for the auto.master map!

FORMAT
This is a description of the text file format. Other methods of specifying these files may exist. All empty lines or lines beginning with # are ignored. The basic format of one line in such maps is:

key [-options] location

  key
is the part of the pathname between the mountpoint and the path into the filesystem mounted. Usually you can think about the key as a subdirectory name below the mountpoint.

  options
Options are optional. Options can also be given in the auto.master file in which case both values are cumulative (this is a difference from SunOS). The options are a list of comma separated options as customary for the mount(8) command. There is a special option -fstype= used to specify a filesystem type if the filesystem is not of the default NFS type. This option is processed by the automounter and not by the mount command.

  location
The location specifies from where the file system is to be mounted. In the most cases this will be an NFS volume and the usual notation host:pathname is used to indicate the remote filesystem and path to be mounted. If the filesystem to be mounted begins with a / (such as local /dev entries or smbfs shares) a : needs to be prefixed (e.g. :/dev/sda1).

EXAMPLE

    kernel	-ro,soft,intr	ftp.kernel.org:/pub/linux
    boot	-fstype=ext2	:/dev/hda1
    windoze	-fstype=smbfs	://windoze/c
    removable	-fstype=ext2	:/dev/hdd
    cd	-fstype=iso9660,ro	:/dev/hdc
    floppy	-fstype=auto	:/dev/fd0

In the first line we have a NFS remote mount of the kernel directory on ftp.kernel.org. This is mounted read-only. The second line mounts an ext2 volume on a local ide drive. The third makes a share exported from a Windows machine available for automounting. The rest should be fairly self-explanatory.

FEATURES

  Map Key Substitution
An & character in the location is expanded to the value of the key field that matched the line (which probably only makes sense together with a wildcard key).

  Wildcard Key
A * in the key field matches all keys. An example for the usefulness is the following entry:

    *	&:/home/&

This will enable you to access all the home directory of local hosts using the path /mountpoint/hostname/local-path.

  Variable Substitution
The following special variables will be substituted in the key and location fields of an automounter map if prefixed with $ as customary from shell scripts (Curly braces can be used to separate the fieldname):

    ARCH	Architecture (uname -m)
    CPU	Processor Type
    HOST	Hostname (uname -n)
    OSNAME	Operating System (uname -s)
    OSREL	Release of OS (uname -r)
    OSVERS	Version of OS (uname -v)

Additional entries can be defined with the -Dvariable=Value option to automount(8).

  Executable Maps
A map can be marked as executable. The init script that parses the auto.master map will pass this as a program map to the automounter. A program map will be called as a script with the key as an argument. The script needs to return one line of a map or no output at all if the key cannot be matched.

To do this the automount(8) daemon has to be started with the program type insted of the file type. This is implemented in the initialization script.

A executable map can return an errorcode to indicate the failure in addition to no output at all. All output sent to stderr is logged into the system logs.

UNSUPPORTED
The automounter does not support direct maps or mount trees (more than one filesystem to be mounted under a specific automount point), and handles SunOS-style replicated filesystems only to the extent that mount(8) does.

SEE ALSO
automount(8), auto.master(5), autofs(8), mount(8).

AUTHOR
This manual page was written by Christoph Lameter <chris@waterf.org>, for the Debian GNU/Linux system. Edited by H. Peter Anvin <hpa@transmeta.com>.