autofs简介
mount是用来挂载文件系统的，可以在系统启动的时候挂载，也可以在系统启动后挂载。
对于本地固定设备，如硬盘可以使用mount挂载，而光盘、软盘、NFS、SMB等文件系统具有动态性，即需要的时候才有必要挂载。
光驱和软盘我们一般知道什么时候需要挂载，但NFS和SMB共享等就不一定知道了，即我们一般不能及时知道NFS共享和SMB什么时候可以挂载。
而autofs服务就提供这种功能，好像windows中的光驱自动打开功能，能够及时挂载动态加载的文件系统，免去我们手动挂载的麻烦。
要实现光驱，软盘等的动态自动挂载，需要进行相关的配置。
下面我们就给出配置的方法。
autofs配置
autofs的主要配置文件有两个，分别是/etc下的auto.master和auto.misc。
其中，auto.master是起控制作用的，它定义了挂在点和automount动作的文件。auto.misc就是automount动作的文件
/etc/auto.master的内容如下：
#
# $Id: auto.master,v 1.4 2005/01/04 14:36:54 raven Exp $
#
# Sample auto.master file
# This is an automounter map and it has the following format
# key [ -mount-options-separated-by-comma ] location
# For details of the format look at autofs(5).
#
/misc /etc/auto.misc --/misc是定义的自动mount的挂载点，/etc/auto.misc里定义了mount的动作（/etc/auto.misc一般为默认的mount文件，还可以自定义）
#
# NOTE: mounts done from a hosts map will be mounted with the
# "nosuid" and "nodev" options unless the "suid" and "dev"
# options are explicitly given.
#
/net -hosts
#
# Include central master map if it can be found using
# nsswitch sources.
#
# Note that if there are entries for /net or /misc (as
# above) in the included master map any keys that are the
# same will not be seen as the first read key seen takes
# precedence.
#
+auto.master
/etc/auto.misc的内容如下：
#
# $Id: auto.misc,v 1.2 2003/09/29 08:22:35 raven Exp $
#
# This is an automounter map and it has the following format
# key [ -mount-options-separated-by-comma ] location
# Details may be found in the autofs(5) manpage
cd -fstype=iso9660,ro,nosuid,nodev :/dev/cdrom --将/dev/cdrom自动挂载到/misc/cd/下
# the following entries are samples to pique your imagination
#linux -ro,soft,intr ftp.example.org:/pub/linux --将ftp.example.org的共享目录/pub/linux/自动挂载到/misc/linux/下
#boot -fstype=ext2 :/dev/hda1 --将本地磁盘分区/dev/hda1自动挂载到/misc/boot下
#floppy -fstype=auto :/dev/fd0 --将软盘设备/dev/fd0自动挂载到/misc/floppy下
#floppy -fstype=ext2 :/dev/fd0
#e2floppy -fstype=ext2 :/dev/fd0
#jaz -fstype=ext2 :/dev/sdc1
#removable -fstype=ext2 :/dev/hdd要访问上面的automount资源，可以用如下命令：
shell> ls /misc/cd/
shell> ls /misc/linux/
shell> ls /misc/boot/
shell> ls /misc/floppy/
这些资源只有在你试图访问的时候才会去自动挂载，而在一段时间之后，如果你不再使用这些资源，autofs会自动卸载这些资源
默认时间为5分钟(300秒)，此选项由/etc/sysconfig/autofs定义，根据需要可以修改。
/etc/sysconfig/autofs的内容如下：
#
# Define default options for autofs.
#
# MASTER_MAP_NAME - default map name for the master map.
#
#MASTER_MAP_NAME="auto.master"
#
# TIMEOUT - set the default mount timeout (default 600).
#
TIMEOUT=300
#
# NEGATIVE_TIMEOUT - set the default negative timeout for
# failed mount attempts (default 60).
#
#NEGATIVE_TIMEOUT=60
#
# UMOUNT_WAIT - time to wait for a response from umount(8).
#
#UMOUNT_WAIT=12
#
# BROWSE_MODE - maps are browsable by default.
#
BROWSE_MODE="no"
#
# APPEND_OPTIONS - append to global options instead of replace.
#
#APPEND_OPTIONS="yes"
#
# LOGGING - set default log level "none", "verbose" or "debug"
#
#LOGGING="none"
#
# Define base dn for map dn lookup.
#
# Define server URIs
#
# LDAP_URI - space seperated list of server uris of the form
# <proto>://<server>[/] where <proto> can be ldap
# or ldaps. The option can be given multiple times.
# Map entries that include a server name override
# this option.
#
# This configuration option can also be used to
# request autofs lookup SRV RRs for a domain of
# the form <proto>:///[<domain dn>]. Note that a
# trailing "/" is not allowed when using this form.
# If the domain dn is not specified the dns domain
# name (if any) is used to construct the domain dn
# for the SRV RR lookup. The server list returned
# from an SRV RR lookup is refreshed according to
# the minimum ttl found in the SRV RR records or
# after one hour, whichever is less.
#
#LDAP_URI=""
#
# LDAP__TIMEOUT - timeout value for the synchronous API calls
# (default is LDAP library default).
#
#LDAP_TIMEOUT=-1
#
# LDAP_NETWORK_TIMEOUT - set the network response timeout (default 8).
#
#LDAP_NETWORK_TIMEOUT=8
#
# SEARCH_BASE - base dn to use for searching for map search dn.
# Multiple entries can be given and they are checked
# in the order they occur here.
#
#SEARCH_BASE=""
#
# Define the LDAP schema to used for lookups
#
# If no schema is set autofs will check each of the schemas
# below in the order given to try and locate an appropriate
# basdn for lookups. If you want to minimize the number of
# queries to the server set the values here.
#
#MAP_OBJECT_CLASS="nisMap"
#ENTRY_OBJECT_CLASS="nisObject"
#MAP_ATTRIBUTE="nisMapName"
#ENTRY_ATTRIBUTE="cn"
#VALUE_ATTRIBUTE="nisMapEntry"
#
# Other common LDAP nameing
#
#MAP_OBJECT_CLASS="automountMap"
#ENTRY_OBJECT_CLASS="automount"
#MAP_ATTRIBUTE="ou"
#ENTRY_ATTRIBUTE="cn"
#VALUE_ATTRIBUTE="automountInformation"
#
#MAP_OBJECT_CLASS="automountMap"
#ENTRY_OBJECT_CLASS="automount"
#MAP_ATTRIBUTE="automountMapName"
#ENTRY_ATTRIBUTE="automountKey"
#VALUE_ATTRIBUTE="automountInformation"
#
# AUTH_CONF_FILE - set the default location for the SASL
# authentication configuration file.
#
#AUTH_CONF_FILE="/etc/autofs_ldap_auth.conf"
#
# MAP_HASH_TABLE_SIZE - set the map cache hash table size.
# Should be a power of 2 with a ratio roughly
# between 1:10 and 1:20 for each map.
#
#MAP_HASH_TABLE_SIZE=1024
#
# General global options
#
# If the kernel supports using the autofs miscellanous device
# and you wish to use it you must set this configuration option
# to "yes" otherwise it will not be used.
USE_MISC_DEVICE="yes"
#
#OPTIONS=""
#应用举例
服务器：192.168.78.142
客户端：192.168.78.143
将服务器上的/home目录自动挂载到客户端/app/home下，要求对挂载过来的/home目录有读写功能
服务器上的/home目录通过nfs共享，需要将服务器上/home目录export出来，客户端还需要能够自动挂载此目录。
1、服务器端共享/home目录
vi /etc/exports
/home 192.168.78.*(rw)
2、客户端配置automount
vi /etc/auto.master添加一行：
/app /etc/auto.home --/app是定义的自动mount的挂载点，/etc/auto.home定义了mount的动作，此文件系统默认不存在，需要我们手工创建在/etc下创建auto.home，并写入一行：
home -rw 192.168.78.142:/home/ --home即为在/app下的home目录，因为在/etc/auto.master文件中已经指定了挂载点了，此处挂载的是远程目录，若挂载本地目录，
不用指定ip地址，直接写 :[要挂载的目录] 即可3、重启autofs服务
service autofs restart
4、查看是否挂载成功
cd /app/home/langkeziju --langkeziju是服务器/home目录下的目录
ls -l --查看下面的文件
total 1
drwx------ 3 langkeziju root 4096 Oct 12 16:33 1.txt
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