210 lines
6.9 KiB
Groff
210 lines
6.9 KiB
Groff
.\" nfs.5 "Rick Sladkey" <jrs@world.std.com>
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.\" Wed Feb 8 12:52:42 1995, faith@cs.unc.edu: updates for Ross Biro's
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.\" patches. "
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.TH NFS 5 "20 November 1993" "Linux 0.99" "Linux Programmer's Manual"
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.SH NAME
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nfs \- nfs fstab format and options
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.SH SYNOPSIS
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.B /etc/fstab
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.SH DESCRIPTION
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The
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.I fstab
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file contains information about which filesystems
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to mount where and with what options.
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For NFS mounts, it contains the server name and
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exported server directory to mount from,
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the local directory that is the mount point,
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and the NFS specific options that control
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the way the filesystem is mounted.
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.P
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Here is an example from an \fI/etc/fstab\fP file from an NFS mount.
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.sp
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.nf
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.ta 2.5i +0.75i +0.75i +1.0i
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server:/usr/local/pub /pub nfs timeo=14,intr
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.fi
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.DT
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.SS Options
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.TP 1.5i
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.I rsize=n
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The number of bytes NFS uses when reading files from an NFS server.
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The default value is dependent on the kernel, currently 1024 bytes.
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.TP 1.5i
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.I wsize=n
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The number of bytes NFS uses when writing files to an NFS server.
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The default value is dependent on the kernel, currently 1024 bytes.
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.TP 1.5i
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.I timeo=n
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The value in tenths of a second before sending the
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first retransmission after an RPC timeout.
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The default value is 7 tenths of a second. After the first timeout,
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the timeout is doubled after each successive timeout until a maximum
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timeout of 60 seconds is reached or the enough retransmissions
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have occured to cause a major timeout. Then, if the filesystem
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is hard mounted, each new timeout cascade restarts at twice the
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initial value of the previous cascade, again doubling at each
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retransmission. The maximum timeout is always 60 seconds.
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Better overall performance may be achieved by increasing the
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timeout when mounting on a busy network, to a slow server, or through
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several routers or gateways.
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.TP 1.5i
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.I retrans=n
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The number of minor timeouts and retransmissions that must occur before
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a major timeout occurs. The default is 3 timeouts. When a major timeout
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occurs, the file operation is either aborted or a "server not responding"
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message is printed on the console.
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.TP 1.5i
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.I acregmin=n
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The minimum time in seconds that attributes of a regular file should
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be cached before requesting fresh information from a server.
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The default is 3 seconds.
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.TP 1.5i
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.I acregmax=n
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The maximum time in seconds that attributes of a regular file can
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be cached before requesting fresh information from a server.
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The default is 60 seconds.
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.TP 1.5i
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.I acdirmin=n
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The minimum time in seconds that attributes of a directory should
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be cached before requesting fresh information from a server.
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The default is 30 seconds.
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.TP 1.5i
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.I acdirmax=n
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The maximum time in seconds that attributes of a directory can
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be cached before requesting fresh information from a server.
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The default is 60 seconds.
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.TP 1.5i
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.I actimeo=n
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Using actimeo sets all of
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.I acregmin,
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.I acregmax,
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.I acdirmin,
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and
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.I acdirmax
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to the same value.
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There is no default value.
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.TP 1.5i
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.I retry=n
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The number of times to retry a backgrounded NFS mount operation
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before giving up.
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The default value is 10000 times.
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.TP 1.5i
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.I namlen=n
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When an NFS server does not support version two of the
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RPC mount protocol, this option can be used to specify
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the maximum length of a filename that is supported on
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the remote filesystem. This is used to support the
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POSIX pathconf functions. The default is 255 characters.
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.TP 1.5i
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.I port=n
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The numeric value of the port to connect to the NFS server on.
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If the port number is 0 (the default) then query the
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remote host's portmapper for the port number to use.
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If the remote host's NFS daemon is not registered with
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its portmapper, the standard NFS port number 2049 is
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used instead.
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.TP 1.5i
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.I mountport=n
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The numeric value of the
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.B mountd
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port.
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.TP 1.5i
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.I mounthost=name
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The name of the host running
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.B mountd .
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.TP 1.5i
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.I mountprog=n
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Use an alternate RPC program number to contact the
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mount daemon on the remote host. This option is useful
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for hosts that can run multiple NFS servers.
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The default value is 100005 which is the standard RPC
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mount daemon program number.
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.TP 1.5i
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.I mountvers=n
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Use an alternate RPC version number to contact the
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mount daemon on the remote host. This option is useful
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for hosts that can run multiple NFS servers.
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The default value is version 1.
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.TP 1.5i
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.I nfsprog=n
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Use an alternate RPC program number to contact the
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NFS daemon on the remote host. This option is useful
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for hosts that can run multiple NFS servers.
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The default value is 100003 which is the standard RPC
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NFS daemon program number.
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.TP 1.5i
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.I nfsvers=n
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Use an alternate RPC version number to contact the
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NFS daemon on the remote host. This option is useful
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for hosts that can run multiple NFS servers.
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The default value is version 2.
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.TP 1.5i
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.I bg
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If the first NFS mount attempt times out, continue trying the mount
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in the background.
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The default is to not to background the mount on timeout but fail.
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.TP 1.5i
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.I fg
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If the first NFS mount attempt times out, fail immediately.
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This is the default.
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.TP 1.5i
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.I soft
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If an NFS file operation has a major timeout then report an I/O error to
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the calling program.
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The default is to continue retrying NFS file operations indefinitely.
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.TP 1.5i
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.I hard
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If an NFS file operation has a major timeout then report
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"server not responding" on the console and continue retrying indefinitely.
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This is the default.
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.TP 1.5i
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.I intr
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If an NFS file operation has a major timeout and it is hard mounted,
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then allow signals to interupt the file operation and cause it to
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return EINTR to the calling program. The default is to not
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allow file operations to be interrupted.
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.TP 1.5i
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.I posix
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Mount the NFS filesystem using POSIX semantics. This allows
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an NFS filesystem to properly support the POSIX pathconf
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command by querying the mount server for the maximum length
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of a filename. To do this, the remote host must support version
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two of the RPC mount protocol. Many NFS servers support only
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version one.
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.TP 1.5i
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.I nocto
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Supress the retrieval of new attributes when creating a file.
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.TP 1.5i
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.I noac
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Disable all forms of attribute caching entirely. This extracts a
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server performance penalty but it allows two different NFS clients
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to get reasonable good results when both clients are actively
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writing to common filesystem on the server.
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.TP 1.5i
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.I tcp
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Mount the NFS filesystem using the TCP protocol instead of the
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default UDP protocol. Many NFS severs only support UDP.
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.TP 1.5i
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.I udp
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Mount the NFS filesystem using the UDP protocol. This
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is the default.
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.P
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All of the non-value options have corresponding nooption forms.
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For example, nointr means don't allow file operations to be
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interrupted.
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.SH FILES
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.I /etc/fstab
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.SH "SEE ALSO"
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.BR fstab "(5), " mount "(8), " umount "(8), " exports (5)
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.SH AUTHOR
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"Rick Sladkey" <jrs@world.std.com>
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.SH BUGS
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The bg, fg, retry, posix, and nocto options are parsed by mount
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but currently are silently ignored.
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.P
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The tcp and namlen options are implemented but are not currently
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supported by the Linux kernel.
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.P
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The umount command should notify the server
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when an NFS filesystem is unmounted.
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