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 map key of * denotes a wild-card entry. This entry is consulted
if the specified key does not exist in the map. A typical wild-
card entry looks like this:
* server:/export/home/&
The special character '&' will be replaced by the provided key.
So, in the example above, a lookup for the key 'foo' would yield
a mount of server:/export/home/foo.
Variable Substitution
The following special variables will be substituted in the
location field of an automounter map entry if prefixed with $ as
customary from shell scripts (curly braces can be used to
separate the field name):
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)
autofs provides additional variables that are set based on the
user requesting the mount:
USER The user login name
UID The user login ID
GROUP The user group name
GID The user group ID
HOME The user home directory
SHOST Short hostname (domain part removed if present)
If a program map is used these standard environment variables
will have a prefix of "AUTOFS_" to prevent interpreted languages
like python from being able to load and execute arbitrary code
from a user home directory.
Additional entries can be defined with the -Dvariable=Value map-
option to automount(8).
Executable Maps
A map can be marked as executable. A program map will be called
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 entry
(with \ quoting line breaks). The map entry corresponds to what
would normally follow a map key.
An executable map can return an error code 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:
key [ -options ] [[/] location [/relative-mount-point [ -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. This behaviour may be overridden by
the append_options configuration setting.
Replicated Server
A mount location can specify multiple hosts for a location,
portentially with a different export path for the same file
system. Historically these different locations are read-only and
provide the same replicated file system.
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
