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:
I key [ -options ] location
key
For indirect mounts this is the part of the pathname between the mountpointi
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
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 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.
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.
R :/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
server -rw,hard,intr / -ro myserver.me.org:/ \ /usr myserver.me.org:/usr \ /home myserver.me.org:/home
In the first line we have a NFS remote mount of the kernel directory on
R 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 autofs map:
floppy-vfat -fstype=vfat,sync,gid=floppy,umask=002 :/dev/fd0
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 of indirect maps 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 map-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. It may
return no lines of output if there's an error, or one or more lines
containing a map (with \ quoting line breaks).
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 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.
Multiple Mounts
A
multi-mount map
can be used to name multiple filesystems to mount. It takes the form:
I 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
default mount-options.
Replicated Server
Multiple replicated hosts, same path:
<path> host1,host2,hostn:/path/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:
<path> host1(5),host2(6),host3(1):/path/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:
<path> host1(3),host:/blah
UNSUPPORTED
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.
CAVEATS
Unlike Sun's multi-mount syntax, the mountpoint is mandatory for all
mounts.
SEE ALSO
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>, Jeremy Fitzhardinge <jeremy@goop.org> and
Ian Kent <raven@themaw.net>.
