linux - nfsd (8)
NAME
nfsd - NFS service daemon
SYNOPSIS
/usr/sbin/rpc.nfsd [ -f exports-file ] [ -d facility ]
[ -P port ] [ -Fhnprstv ] [ --debug facility ]
[ --exports-file=file ] [ --foreground ] [ --help ]
[ --allow-non-root ] [ --re-export ] [ --port port ]
[ --version ] [ numservers ]
DESCRIPTION
The nfsd program is an NFS service daemon that handles
client filesystem requests. Unlike on some other systems,
nfsd operates as a normal user-level process. The server
also differs from other NFS server implementations in that
it mounts an entire file hierarchy not limited by the
boundaries of physical file-systems. The implementation
allows the clients read-only or read-write access to the
file hierarchy of the server machine.
The mountd program starts an ancillary user-level mount
daemon.
OPTIONS
-f or --exports-file
This option specifies the exports file, listing the
clients that this server is prepared to serve and
parameters to apply to each such mount (see
exports(5)). By default exports are read from
/etc/exports.
-d facility or --debug facility
Log operations verbosely. Legal values for facility
are currently call for the logging of RPC calls and
arguments, fhcache for the file handle cache opera-
tion, auth for the authentication routines, and
ugid for the uid mapping code, if used. Debug mes-
sages will be logged to syslog(8) unless the daemon
runs in the foreground.
-F or --foreground
Unlike in normal operation, nfsd will not detach
from the terminal when given this option. When
debugging is requested, it will be sent to standard
error.
-h or --help
Provide a short help summary.
-n or --allow-non-root
Allow incoming NFS requests to be honored even if
Some newer NFS client implementations don't believe
in reserved port checking. This check can be turned
off for individual hosts by specifying the insecure
export option in /etc/exports.
-P portnum or --port portnum
Makes nfsd listen on port portnum instead of the
default port 2049.
-p or --promiscuous
Put the server into promiscuous mode where it will
serve any host on the network.
-r or --re-export
Allow imported NFS file-systems to be exported.
This can be used to turn a machine into an NFS mul-
tiplier. Caution should be used when re-exporting
loopback NFS mounts because re-entering the mount
point will result in deadlock between the NFS
client and the NFS server.
-v or --version
Report the current version number of the program.
numcopies
This is an experimental feature that lets you run
several instances of nfsd in parallel. When given a
value of numcopies greater than one, nfsd will fork
as many times as specified by this value. However,
the servers do not share a common file handle
cache, which makes certain file operations impossi-
ble.
For this reason, nfsd will disallow all write oper-
ations when invoked with this option. Although this
is very limiting, this feature may still prove use-
ful for exporting public FTP areas or Usenet News
spools. Note that (at best) you won't see any
improvements when measuring throughput with a sin-
gle reader, or with several readers on a single
host whose NFS client implementation is single-
threaded and does no read-ahead (as Linux's cur-
rently is).
SIGNALS
nfsd recognizes the following signals:
SIGHUP causes nfsd to re-read the export file and flush
the file handle cache.
SIGUSR1
When nfsd was invoked with debugging options, send-
SIGIOT When compiled with with the -DCALL_PROFILING
option, sending a SIGIOT to nfsd will cause dump
the average execution times per NFS operation into
/tmp/nfsd.profile.
SEE ALSO
exports(5), mountd(8), ugidd(8C)
AUTHORS
Mark Shand wrote the orignal unfsd. Don Becker extended
unfsd to support authentication and allow read-write
access and called it hnfs. Rick Sladkey added host match-
ing, showmount -e support, mountd authentication, inetd
support, and all of the portability and configuration
code. Olaf Kirch fixed one or two security holes and
other bugs, added the uid mapping and a couple of other
things.