1exportfs(8) System Manager's Manual exportfs(8)
2
6 exportfs - maintain table of exported NFS file systems
7
9 /usr/sbin/exportfs [-avi] [-o options,..] [client:/path ..]
10 /usr/sbin/exportfs -r [-v]
11 /usr/sbin/exportfs [-av] -u [client:/path ..]
12 /usr/sbin/exportfs [-v]
13 /usr/sbin/exportfs -f
14 /usr/sbin/exportfs -s
15
17 An NFS server maintains a table of local physical file systems that are
18 accessible to NFS clients. Each file system in this table is referred
19 to as an exported file system, or export, for short.
20 The exportfs command maintains the current table of exports for the NFS
22 server. The master export table is kept in a file named
23 /var/lib/nfs/etab. This file is read by rpc.mountd when a client sends
24 an NFS MOUNT request.
25 Normally the master export table is initialized with the contents of
27 /etc/exports and files under /etc/exports.d by invoking exportfs -a.
28 However, a system administrator can choose to add or delete exports
29 without modifying /etc/exports or files under /etc/exports.d by using
30 the exportfs command.
31 exportfs and its partner program rpc.mountd work in one of two modes: a
33 legacy mode which applies to 2.4 and earlier versions of the Linux ker‐
34 nel, and a new mode which applies to 2.6 and later versions, providing
35 the nfsd virtual filesystem has been mounted at /proc/fs/nfsd or
36 /proc/fs/nfs. On 2.6 kernels, if this filesystem is not mounted, the
37 legacy mode is used.
38 In the new mode, exportfs does not give any information to the kernel,
40 but provides it only to rpc.mountd through the /var/lib/nfs/etab file.
41 rpc.mountd then manages kernel requests for information about exports,
42 as needed.
43 In the legacy mode, exports which identify a specific host, rather than
45 a subnet or netgroup, are entered directly into the kernel's export ta‐
46 ble, as well as being written to /var/lib/nfs/etab. Further, exports
47 listed in /var/lib/nfs/rmtab which match a non host-specific export
48 request will cause an appropriate export entry for the host given in
49 rmtab to be added to the kernel's export table.
50
52 -d kind or --debug kind
53 Turn on debugging. Valid kinds are: all, auth, call, general and
54 parse. Debugging can also be turned on by setting debug= in the
55 [exportfs] section of /etc/nfs.conf.
56 -a Export or unexport all directories.
59 -o options,...
61 Specify a list of export options in the same manner as in
62 exports(5).
63 -i Ignore the /etc/exports file and files under /etc/exports.d
65 directory. Only default options and options given on the com‐
66 mand line are used.
67 -r Reexport all directories, synchronizing /var/lib/nfs/etab with
69 /etc/exports and files under /etc/exports.d. This option
70 removes entries in /var/lib/nfs/etab which have been deleted
71 from /etc/exports or files under /etc/exports.d, and removes any
72 entries from the kernel export table which are no longer valid.
73 -u Unexport one or more directories.
75 -f If /proc/fs/nfsd or /proc/fs/nfs is mounted, flush everything
77 out of the kernel's export table. Fresh entries for active
78 clients are added to the kernel's export table by rpc.mountd
79 when they make their next NFS mount request.
80 -v Be verbose. When exporting or unexporting, show what's going on.
82 When displaying the current export list, also display the list
83 of export options.
84 -s Display the current export list suitable for /etc/exports.
86
89 The [exportfs] section of the /etc/nfs.conf configuration file can con‐
90 tain a debug value, which can be one or more from the list general,
91 call, auth, parse, all. When a list is given, the members should be
92 comma-separated.
93 exportfs will also recognize the state-directory-path value from both
95 the [mountd] section and the [exportd] section
96
99 Exporting Directories
100 The first synopsis shows how to invoke exportfs when adding new entries
101 to the export table. When using exportfs -a, all exports listed in
102 /etc/exports and files under /etc/exports.d are added to
103 /var/lib/nfs/etab. The kernel's export table is also updated as
104 needed.
105 The host:/path argument specifies a local directory to export, along
107 with the client or clients who are permitted to access it. See
108 exports(5) for a description of supported options and access list for‐
109 mats.
110 IPv6 presentation addresses contain colons, which are already used to
112 separate the "host" and "path" command line arguments. When specifying
113 a client using a raw IPv6 address, enclose the address in square brack‐
114 ets. For IPv6 network addresses, place the prefix just after the clos‐
115 ing bracket.
116 To export a directory to the world, simply specify :/path.
118 The export options for a particular host/directory pair derive from
120 several sources. The default export options are
121 sync,ro,root_squash,wdelay. These can be overridden by entries in
122 /etc/exports or files under /etc/exports.d.
123 A system administrator may override options from these sources using
125 the -o command-line option on exportfs. This option takes a comma-sep‐
126 arated list of options in the same fashion as one would specify them in
127 /etc/exports. In this way exportfs can be used to modify the export
128 options of an already exported directory.
129 Unexporting Directories
131 The third synopsis shows how to unexport a currently exported direc‐
132 tory. When using exportfs -ua, all entries listed in /var/lib/nfs/etab
133 are removed from the kernel export tables, and the file is cleared.
134 This effectively shuts down all NFS activity.
135 To remove an export, specify a host:/path pair. This deletes the speci‐
137 fied entry from /var/lib/nfs/etab and removes the corresponding kernel
138 entry (if any).
139 Dumping the Export Table
141 Invoking exportfs without options shows the current list of exported
142 file systems. Adding the -v option causes exportfs to display the
143 export options for each export.
144
146 The following adds all directories listed in /etc/exports and files
147 under /etc/exports.d to /var/lib/nfs/etab and pushes the resulting
148 export entries into the kernel:
149 # exportfs -a
151 To export the /usr/tmp directory to host django, allowing insecure file
153 locking requests from clients:
154 # exportfs -o insecure_locks django:/usr/tmp
156 To unexport the /usr/tmp directory:
158 # exportfs -u django:/usr/tmp
160 To unexport all exports listed in /etc/exports and files under
162 /etc/exports.d:
163 # exportfs -au
165 To export the /usr/tmp directory to IPv6 link-local clients:
167 # exportfs [fe80::]/64:/usr/tmp
169
171 Exporting to IP networks or DNS and NIS domains does not enable clients
172 from these groups to access NFS immediately. Rather, these sorts of
173 exports are hints to rpc.mountd(8) to grant any mount requests from
174 these clients. This is usually not a problem, because any existing
175 mounts are preserved in rmtab across reboots.
176 When unexporting a network or domain entry, any current exports to mem‐
178 bers of this group will be checked against the remaining valid exports
179 and if they themselves are no longer valid they will be removed.
180
182 /etc/exports input file listing exports, export options,
183 and access control lists
184 /etc/exports.d directory where extra input files are stored.
186 Note: only files that end with .exports are
187 used.
188 /var/lib/nfs/etab master table of exports
190 /var/lib/nfs/rmtab table of clients accessing server's exports
192
194 exports(5), nfs.conf(5), rpc.mountd(8), exportd(8), netgroup(5)
195
197 Olaf Kirch <okir@monad.swb.de>
198 Neil Brown <neilb@cse.unsw.edu.au>
199 30 September 2013 exportfs(8)