term% cat index.txt EXPORTFS(4) Kernel Interfaces Manual 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:
-A address
Use the network address to announce aan(8) connections, if re‐
quested by the initial protocol.
-a Authenticate the user with the p9any protocol before running the
regular exportfs session; used when exportfs is invoked to han‐
dle 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 en‐
crypting 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 ser‐
vice. 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 cre‐
ated with mode perm (default 0600). The name space is the directory
tree rooted at path. The -d, -P, and -R options, if present, are re‐
layed to exportprog.
EXAMPLES
To export the archive of one user for one month, except for secrets,
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)
EXPORTFS(4)