.TH EXPORTFS 4
.SH NAME
exportfs, srvfs \- network file server plumbing
.SH SYNOPSIS
.B exportfs
[
.B -adnsR
] [
.B -f
.I dbgfile
] [
.B -m
.I msize
] [
.B -r
.I root
] [
.B -S
.I service
] [
.B -A announce
] [
.B -e
.I "'enc auth'"
] [
.B -N
.I nsfile
] [
.B -P
.I patternfile
]
.PP
.B srvfs
[
.B -dR
]
[
.B -p
.I perm
]
[
.B -P
.I patternfile
] [
.B -e
.I exportprog
]
.I name
.I path
.SH DESCRIPTION
.I 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
.IR cpu (1)
command or by a network listener process.  An initial protocol
establishes a root directory for the exported name space.
The
connection to
.I exportfs
is then mounted, typically on
.BR /mnt/term .
.I 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.
.PP
.I Exportfs
creates a new name space for each connection, using
.B /lib/namespace
by default (see
.IR namespace (6)).
The
.B -n
option gives an alternative name space file.
.PP
The
.B -R
option makes the served name space read only.
.PP
The 
.B -r
option bypasses the initial protocol, instead immediately
serving the name space rooted at 
.IR root .
The
.B -s
option is equivalent to
.B -r 
.BR / ,
but predates
.B -r
and remains for compatibility.
.PP
The
.B -S
option also bypasses the initial protocol but
serves the result of mounting
.IR service .
A separate mount is used for each
.IR attach (5)
message,
to correctly handle servers in which each mount
corresponds to a different client
.IR e.g. , (
.IR rio (4)).
.PP
The
.B -m
option sets the maximum message size that 
exportfs should offer to send (see
.IR version (5));
this helps tunneled
9P connections to avoid unnecessary fragmentation.
.PP
The
.B -a
option instructs
.I exportfs
to authenticate the user, usually because it is
being invoked from a remote machine.
.PP
The
.B -d
option instructs
.I exportfs
to log all 9P traffic to 
.I dbgfile
(default
.BR /tmp/exportdb ).
.PP
The
.BI  -P patternfile
option restricts the set of exported files.
.I Patternfile
contains one regular expression per line,
to be matched against path names
relative to the current working directory
and starting with
.BR ./ .
For a file to be exported, all lines with a prefix
.B +
must match and all those with prefix
.B -
must not match.
.PP
The
.B -e
option specifies the encryption and authentication algorithms to use for
encrypting the wire traffic.  The defaults are
.B rc4_256
and
.BR sha1 .
The full list of supported protocols in in
.IR ssl (3).
.PP
The
.B cpu
command uses
.I exportfs
to serve device files in the terminal.  The
.IR import (4)
command calls
.I 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
.BR /srv ),
.I exportfs
calls itself (with appropriate
.B -m
and
.B -S 
options) to simulate reads and writes on such files.
.PP
.I Srvfs
invokes
.I exportprog
(default
.BR /bin/exportfs )
to create a mountable file system from a name space
and posts it at
.BI /srv/ name ,
which is created with mode
.I perm
(default 0600).
By default, the name space is the directory tree rooted at 
.IR path .
If the
.BR -d ,
.BR -R ,
or
.B -P
options are given,
.I srvfs
passes them to
.IR exportprog .
.PP
The
.B -A
filter specifies an announce string when exportfs is used in combination
with aan.  The announce string identifies the network and network 
protocol to use for aan connections.
.SH EXAMPLES
To export the archive of one user for one month, except for secrets,
.IP
.EX
cd /n/dump
echo '+ ^\.(/2003(/10..(/usr(/glenda/?)?)?)?)?' > /tmp/pattern
echo '- \.(aes|pgp)$' >> /tmp/pattern
exportfs -p /tmp/pattern
.EE
.LP
Use
.I srvfs
to enable mounting of an FTP file system (see
.IR ftpfs (4))
in several windows, 
or to publish a
.B /proc
(see
.IR proc (3))
with a broken process so a remote person may debug the program:
.IP
.EX
srvfs ftp /n/ftp
srvfs broke /mnt/term/proc
.EE
.LP
Use 
.I srvfs
to obtain a copy of a service to be manipulated directly
by a user program like
.IR nfsserver (8):
.IP
.EX
srvfs nfs.boot /srv/boot
aux/nfsserver -f /srv/nfs.boot
.EE
.LP
Use
.I srvfs
to spy on all accesses to a particular subtree:
.IP
.EX
srvfs -d spy /
tail -f /tmp/exportdb &
mount /srv/spy /n/spy
cd /n/spy; ls
.EE
.SH SOURCE
.B /sys/src/cmd/exportfs
.br
.B /sys/src/cmd/srvfs.c
.SH SEE ALSO
.IR aan (8),
.IR import (4),
.IR exportfs (4)