xref: /plan9/sys/man/4/exportfs (revision 6bbfed0d85c6d7248503ef0614d0f1e40438b735)
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 compute 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 process. 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: .TF "-A address"

-A address Use the network address to announce aan (8) connections, 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\fL' Set the encryption and authentication algorithms to use for encrypting the wire traffic (see ssl (3)). The defaults are rc4_256 and sha1 .

-m msize Set the maximum message size that exportfs should offer to send (see version (5)); this helps tunneled 9P connections to avoid unnecessary 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 current working directory and starting with ./ . For a file to be exported, all lines with a prefix + 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,
.EX cd /n/dump echo '+ ^\e.(/2003(/10..(/usr(/glenda/?)?)?)?)?' > /tmp/pattern echo '- \e.(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:

.EX 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):

.EX srvfs nfs.boot /srv/boot aux/nfsserver -f /srv/nfs.boot

Use srvfs to spy on all accesses to a particular subtree:

.EX 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)