EXPORTFS(4) EXPORTFS(4)
NAME
exportfs, srvfs - network file server plumbing
SYNOPSIS
exportfs [ options ]
srvfs [ -dR ] [ -p perm ] [ -P patternfile ] [ -e exportprog
] name path
DESCRIPTION
Exportfs is a user level file server that allows Plan 9 com-
pute servers, rather than file servers, to export portions
of a name space across networks. The service is started
either by the cpu(1) command or by a network listener pro-
cess. An initial protocol establishes a root directory for
the exported name space. The connection to exportfs is then
mounted, typically on /mnt/term. Exportfs then acts as a
relay file server: operations in the imported file tree are
executed on the remote server and the results returned.
This gives the appearance of exporting a name space from a
remote machine into a local file tree.
The options are:
-A address Use the network address to announce aan(8) con-
nections, if requested by the initial protocol.
-a Authenticate the user with the p9any protocol
before running the regular exportfs session;
used when exportfs is invoked to handle an
incoming network connection. Exportfs creates a
new name space for each connection, using
/lib/namespace by default (see namespace(6)).
-B address Dial address, authenticate as a p9any client,
and then serve that network connection.
Requires setting the root of the name space with
-r or -s. The remote system should run import
-B to handle the call. See import(4) for an
example.
-d -f dbgfile
Log all 9P traffic to dbgfile (default
/tmp/exportdb).
-e 'enc auth'
Set the encryption and authentication algorithms
to use for encrypting the wire traffic (see
ssl(3)). The defaults are rc4_256 and sha1.
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EXPORTFS(4) EXPORTFS(4)
-m msize Set the maximum message size that exportfs
should offer to send (see version(5)); this
helps tunneled 9P connections to avoid unneces-
sary fragmentation.
-N nsfile Serve the name space described by nsfile.
-n Disallow mounts by user none.
-P patternfile
Restrict the set of exported files. Patternfile
contains one regular expression per line, to be
matched against path names relative to the cur-
rent working directory and starting with ./.
For a file to be exported, all lines with a pre-
fix + must match and all those with prefix -
must not match.
-R Make the served name space read only.
-r root Bypass the initial protocol, serving the name
space rooted at root. A corresponding import(4)
must use the -m option.
-S service Bypass the initial protocol, serving the result
of mounting service. A separate mount is used
for each attach(5) message, to correctly handle
servers in which each mount corresponds to a
different client (e.g., rio(4)). A corresponding
import(4) must use the -m option.
-s equivalent to -r /; kept for compatibility.
The cpu command uses exportfs to serve device files in the
terminal. The import(4) command calls exportfs on a remote
machine, permitting users to access arbitrary pieces of name
space on other systems.
Because the kernel disallows reads and writes on mounted
pipes (as might be found in /srv), exportfs calls itself
(with appropriate -m and -S options) to simulate reads and
writes on such files.
Srvfs invokes exportprog (default /bin/exportfs) to create a
mountable file system from a name space and posts it at
/srv/name, which is created with mode perm (default 0600).
The name space is the directory tree rooted at path. The -d,
-P, and -R options, if present, are relayed to exportprog.
EXAMPLES
To export the archive of one user for one month, except for
secrets,
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EXPORTFS(4) EXPORTFS(4)
cd /n/dump
echo '+ ^\.(/2003(/10..(/usr(/glenda/?)?)?)?)?' > /tmp/pattern
echo '- \.(aes|pgp)$' >> /tmp/pattern
exportfs -P /tmp/pattern
Use srvfs to enable mounting of an FTP file system (see
ftpfs(4)) in several windows, or to publish a /proc (see
proc(3)) with a broken process so a remote person may debug
the program:
srvfs ftp /n/ftp
srvfs broke /mnt/term/proc
Use srvfs to obtain a copy of a service to be manipulated
directly by a user program like nfsserver(8):
srvfs nfs.boot /srv/boot
aux/nfsserver -f /srv/nfs.boot
Use srvfs to spy on all accesses to a particular subtree:
srvfs -d spy /
tail -f /tmp/exportdb &
mount /srv/spy /n/spy
cd /n/spy; ls
SOURCE
/sys/src/cmd/exportfs
/sys/src/cmd/srvfs.c
SEE ALSO
dial(2), import(4), aan(8), listen(8)
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