.BR nfs
file system type and specify
.BR nfsvers=2 .
-Version 2 is the default protocol version for the
-.BR nfs
-file system type when
-.BR nfsvers=
-is not specified on the mount command.
To mount via NFS version 3, use the
.BR nfs
file system type and specify
.BR nfsvers=3 .
+Version 3 is the default protocol version for the
+.BR nfs
+file system type when
+.BR nfsvers=
+is not specified on the mount command and both client and server
+support it.
To mount via NFS version 4, use the
.BR nfs4
file system type.
These file system types share similar mount options;
the differences are listed below.
.P
-Here is an example from an \fI/etc/fstab\fP file for an NFSv2 mount
-over UDP.
+Here is an example from an \fI/etc/fstab\fP file for an NFSv3 mount
+over TCP.
.sp
.nf
.ta 2.5i +0.75i +0.75i +1.0i
.I nolock
Disable NFS locking. Do not start lockd.
This has to be used with some old NFS servers
-that don't support locking.
+that don't support locking. Note that applications can
+still get locks on files, but the locks only provide exclusion
+locally. Other clients mounting the same filesystem
+will not be able to detect the locks.
.TP 1.5i
.I bg
If the first NFS mount attempt times out, retry the mount
or privacy.
.TP 1.5i
.I tcp
-Mount the NFS filesystem using the TCP protocol instead of the
-default UDP protocol. Many NFS servers only support UDP.
+Mount the NFS filesystem using the TCP protocol. This is the default
+if it is supported by both client and server. Many NFS servers only
+support UDP.
.TP 1.5i
.I udp
-Mount the NFS filesystem using the UDP protocol. This
-is the default.
+Mount the NFS filesystem using the UDP protocol.
.P
All of the non-value options have corresponding nooption forms.
For example, nointr means don't allow file operations to be
.SH AUTHOR
"Rick Sladkey" <jrs@world.std.com>
.SH BUGS
-The posix, and nocto options are parsed by mount
-but currently are silently ignored.
-.P
-The tcp and namlen options are implemented but are not currently
-supported by the Linux kernel.
-.P
-The umount command should notify the server
-when an NFS filesystem is unmounted.
.P
Checking files on NFS filesystem referenced by file descriptors (i.e. the
.BR fcntl