System Administration Guide: Network Services

Maps That Refer to Other Maps

A map entry +mapname that is used in a file map causes automount to read the specified map as if it were included in the current file. If mapname is not preceded by a slash, autofs treats the map name as a string of characters and uses the name-service switch policy to find the map name. If the path name is an absolute path name, automount checks a local map of that name. If the map name starts with a dash (-), automount consults the appropriate built-in map, such as hosts.

This name-service switch file contains an entry for autofs that is labeled as automount, which contains the order in which the name services are searched. The following file is an example of a name-service switch file.

# /etc/nsswitch.nis:
# An example file that could be copied over to /etc/nsswitch.conf;
# it uses NIS (YP) in conjunction with files.
# "hosts:" and "services:" in this file are used only if the /etc/netconfig
# file contains "" as a nametoaddr library for "inet" transports.
# the following two lines obviate the "+" entry in /etc/passwd and /etc/group.
passwd:         files nis
group:          files nis

# consult /etc "files" only if nis is down.
hosts:          nis [NOTFOUND=return] files
networks:       nis [NOTFOUND=return] files
protocols:      nis [NOTFOUND=return] files
rpc:            nis [NOTFOUND=return] files
ethers:         nis [NOTFOUND=return] files
netmasks:       nis [NOTFOUND=return] files
bootparams:     nis [NOTFOUND=return] files
publickey:      nis [NOTFOUND=return] files
netgroup:       nis
automount:      files nis
aliases:        files nis
# for efficient getservbyname() avoid nis
services:       files nis 

In this example, the local maps are searched before the NIS maps. Therefore, you can have a few entries in your local /etc/auto_home map for the most commonly accessed home directories. You can then use the switch to fall back to the NIS map for other entries.


After consulting the included map, if no match is found, automount continues scanning the current map. Therefore, you can add more entries after a + entry.


The map that is included can be a local file or a built-in map. Remember, only local files can contain + entries.

+auto_home_finance      # NIS+ map
+auto_home_sales        # NIS+ map
+auto_home_engineering  # NIS+ map
+/etc/auto_mystuff      # local map
+auto_home              # NIS+ map
+-hosts                 # built-in hosts map 

Note –

You cannot use + entries in NIS+ or NIS maps.