AUTOFS(5) File Formats Manual AUTOFS(5)
AUTOFS(5) File Formats Manual AUTOFS(5)
autofs - Format of the automounter maps
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 for-
mat; if another map format is specified (e.g. hesiod), this documenta-
tion 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!
This is a description of the text file format. Other methods of speci-
fying 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
For indirect mounts this is the part of the pathname between the mount-
pointi and the path into the filesystem mounted. Usually you can think
about the key as a subdirectory name below the mountpoint.
For direct mounts this is the full path of the mountpoint. This map is
always associated with the /- mountpoint in the master map.
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 cus-
tomary for the mount(8) command. There are two special options -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. -strict is used to treat errors when mounting
file systems as fatal. This is important when multiple file systems
should be mounted (`multimounts'). If this option is given, no file
system is mounted at all if at least one file system can't be mounted.
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.
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
server -rw,hard,intr / -ro myserver.me.org:/ \
/usr myserver.me.org:/usr \
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. The last entry (the last three lines) is an
example of a multi-map (see below).
If you use the automounter for a filesystem without access permissions
(like vfat), users usually can't write on such a filesystem because it
is mounted as user root. You can solve this problem by passing the
option gid=<gid>, e. g. gid=floppy. The filesystem is then mounted as
group floppy instead of root. Then you can add the users to this group,
and they can write to the filesystem. Here's an example entry for an
floppy-vfat -fstype=vfat,sync,gid=floppy,umask=002 :/dev/fd0
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).
A * in the key field of indirect maps matches all keys. An example for
the usefulness is the following entry:
This will enable you to access all the home directory of local hosts
using the path /mountpoint/hostname/local-path.
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 field-
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 map-option
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. It
may return no lines of output if there's an error, or one or more lines
containing a map (starting with the second column, i.e. omitting the
key, and quoting line breaks with \).
To use a program map, the automount(8) daemon has to be started with
the program type instead of the file type. This is implemented in the
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.
A multi-mount map can be used to name multiple filesystems to mount.
It takes the form:
key [-options] [mountpoint [-options] location...]...
This may extend over multiple lines, quoting the line-breaks with `\'.
If present, the per-mountpoint mount-options are appended to the
Multiple replicated hosts, same path:
Multiple hosts, some with same path, some with another
<path> host1,host2:/blah host3:/some/other/path
Multiple replicated hosts, different (potentially) paths:
<path> host1:/path/pathA host2:/path/pathB
Mutliple weighted, replicated hosts same path:
Multiple weighted, replicated hosts different (potentially) paths:
<path> host1(3):/path/pathA host2(5):/path/pathB
Anything else is questionable and unsupported, but these variations will also work:
This version of the automounter supports direct maps for FILE, NIS and
LDAP maps only and handles SunOS-style replicated filesystems only to
the extent that mount(8) does.
Unlike Sun's multi-mount syntax, the mountpoint is mandatory for all
automount(8), auto.master(5), autofs(8), mount(8).
This manual page was written by Christoph Lameter <chrisATwaterf.org>,
for the Debian GNU/Linux system. Edited by H. Peter Anvin <hpa@trans-
meta.com>, Jeremy Fitzhardinge <jeremyATgoop.org> and Ian Kent
14 Jan 2000 AUTOFS(5)