automount.8nfs

<B>Digital的Unix操作系统VAX 4.2源码</B>

are both hosts on a
local area network that is running Yellow Pages.
If the 
.PN /etc/rc.local
file on 
.PN hera
contains the command 
.PN "automount /net \-hosts" ,
then users on 
.PN hera 
can access any directories that 
.PN sheba 
exports to 
.PN hera .
All of the exported directories are mounted under
.PN /net/sheba 
on 
.PN hera .
.PP
The 
.PN \-null
map, when indicated on the command line, cancels the map associated with
the directory indicated.  It can be used to cancel a map specified in the
master map.  For example, invoking the
.PN automount
command in the following manner causes the 
.PN /net
entry in 
.PN auto.master
to be ignored:
.EX
# \f(CBautomount /net \-null\f(CW
.EE
.SS Pattern Matching
The ampersand (&)
is expanded into the key field in 
a map wherever it appears.  In the following example, 
the ampersand (&) expands to
.PN oak :
.EX
        #key      mount_options	     location
        #
        oak                           &:/export/&
.EE
.PP
The asterisk (*), when supplied as the key field, is recognized as the
catch-all entry.  It is used to substitute for lines that are all 
formatted similarly. 
Any entry following the asterisk is ignored.  
In the following example, the
.PN automount 
program uses the asterisk to match any hostname other than 
.PN oak :
.EX
	#key         mount_options        location
	#
	oak                               &:/export/&
	*                                 &:/home/&
.EE
.SS Environment Variables
The value of an environment variable can be used within an automount map
by prefixing a dollar sign ($)
to its name.  You can also use braces to delimit the name of the
variable from appended letters or digits.  The environment variables
can be inherited from the environment or can be explicitly defined with
the 
.PN \-D 
command line option.
.SS Hierarchical Mounts
You can mount different directories within an 
.PN automount
file system hierarchy from different servers.  For example,
if you are mounting the 
.PN /usr/local
file system on your machine, you can mount the various 
subdirectories within 
.PN /usr/local
from different servers.
.PP
In the following example, the directories
.PN /usr/local ,
.PN /usr/local/bin ,
.PN /usr/local/src ,
and
.PN /usr/local/tools
are mounted from the machines host1, host2, host3, and host4
respectively.  When the root of the hierarchy is referenced,
the
.PN automount
program mounts the whole hierarchy.
.PP
.EX

/usr/local\\
		/         -ro       host1:/usr/local \\
		/bin      -ro       host2:/usr/local/bin \\
		/src      -ro       host2:/usr/local/src \\
		/tools    -ro       host2:/usr/src/tools
.EE
.PP
Readability has been improved by splitting the entry into five
lines and indenting the continuation lines.
.SH Options
.NXR "automount command" "options"
.IP \-m 10 
Ignores directory-mapname pairs listed in the
.PN /etc/auto.master 
Yellow Pages database.
.IP \-n 10 
Disables dynamic mounts.  Lookups intercepted by the 
.PN automount
daemon succeed when the target file system has been previously 
mounted.
.IP \-T 10 
Traces all NFS requests received by the daemon.  Information about
the details of the request are expanded and sent to standard output.
.IP \-v 10 
Logs status messages to the console.  (Stands for ``verbose.'')
.IP "\-D \fIname\fR=\fIvalue\fR" 10 
Defines an 
.PN automount
environment variable by assigning
.I value
to the 
variable. 
.\".I  name
.\"and assigns it the value
.\".I value
.\"to be used in 
.\".PN automount 
.\"maps.
.IP "\-f \fImaster-file\fR" 10 
Uses \fImaster-file\fR 
for a list of initial directory to mapname pairs, ahead of the 
.PN auto.master 
Yellow Pages map.  If an entry exists in both
.I master-file
and
.PN auto.master ,
that specified in 
.I master-file
is used since it is read first.  Similarly, entries on the
command line take precedence over 
.I master-file
entries.  This technique can be used to replace entries in 
global maps with your own.
.IP "\-M \fImount-directory\fR" 10 
Uses 
.I mount-directory 
instead of the default,
.PN /tmp_mnt .
.IP "\-tl \fIduration\fR" 10
Specifies a
.I duration
in seconds, that a file system is to remain mounted when not in use.
The default is 5 minutes.
.IP "\-tm \fIinterval\fR" 10
Specifies an
.I interval
in seconds, between attempts to mount a file system. The default
is 30 seconds.
.IP "\-tw \fIinterval\fR" 10
Specifies an   
.I interval
in seconds, between attempts to unmount file systems that have exceeded
their cached times. The default is 1 minute.
.\".IP "-t \fIsub-options\fR" 10
.\"Specify the NFS mount options.  All mount options 
.\"apply except background
.\".PN (bg) 
.\"and foreground (
.\".PN (fg).
.\".IP "\fIdirectory\fR" 10  
.\"Specifies the mount point for
.\".PN automount
.\"itself.  
.\".I Directory
.\"is an absolute pathname starting with a slash ( / ).  If the
.\"directory does not exist, it is created by the 
.\".PN automount
.\"daemon and is removed when the daemon exits.
.\".IP "\fImapname\fR" 10 
.\"Specifies the name of the map file that 
.\".PN automount 
.\"is searching for.  The
.\".PN automount 
.\"command first searches locally for a file called 
.\".I mapname.
.\"If the file does not exist, 
.\".PN automount 
.\"looks for a Yellow Pages map called
.\".I mapname.
.IP \fI\-mount_options\fR 10 
Specifies the mount options to be applied to all of the directories listed
in 
.I mapname.  
If mount options are listed in the specified map, they take precedence
over these options.
.NT
Sending the SIGTERM signal to the 
.PN automount
daemon causes it to unmount all file systems that it has 
mounted, and to exit.
.sp
Sending the SIGHUP signal to the 
.PN automount
daemon causes it to reread the system mount table to update its internal
record of currently mounted file systems.  If a file system mounted
with
.PN automount
is unmounted by a 
.PN umount
command, 
.PN automount
should be forced to reread the system mount table.
.NE
.SH Restrictions
Shell filename expansion does not apply to objects not currently
mounted.
.PP
Because 
.PN automount
is single-threaded, any request that is delayed by a slow or
non-responding NFS server will delay all subsequent 
.PN automount
requests
until the delayed request has been completed.
.SH Examples
The following is a sample
.PN auto.master
map:
.EX 
#
# mount-point           mapname           mount-options
#
/net                    -hosts		
/home                   auto.indirect     -rw
/-                      auto.direct       -ro,intr
.EE
The following is a typical 
.PN automount 
indirect map: 
.EX
#
# key               mount-options         location
#
john                                      merge:/home/merge/john
mary                                      stripe:/home/stripe/mary
fred                                      blur:/usr/staff/fred
.EE
The following is a typical 
.PN automount 
direct map: 
.EX
#
# key               mount-options         location
#
/usr/source         -ro                   merge:/usr/src/proto
/usr/local                                blur:/usr/bin/tools
.EE
The following is a sample indirect map that specifies multiple
mount locations for the file system
.PN reference .
The file system is mounted from the first server to respond to 
the
.PN mount 
request. 
.EX
reference           \-ro            earl:/usr/src/ref\\
                                   fern:/usr/staff/ron/ref\\
                                   irv:/usr/backup/reference
.EE
.SH Files
.TP 15
.PN /tmp_mnt
Directory where automounted file systems reside
.SH See Also
mount(8), mount(8nfs), umount(8)
.br
\fIGuide to the Network File System\fP