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AIX Version 4.3 Commands Reference, Volume 1

chnfsmnt Command

Purpose

Changes the options used to mount a directory from an NFS server.

Syntax

/usr/sbin/chnfsmnt -f PathName -d RemoteDirectory -h RemoteHost-trw | ro } ] [ -m MountTypeName ] [ -wfg | bg } ] [ -X | -x ] [ -S | -H ] [ -Y | -y ] [ -Z | -z ] [ -e -E ]  [ -a | -A ] [ -s | -n ] [ -I | -B | -N ] [ -r TimesToRetry ] [ -b ReadBufferSize ] [ -c WriteBufferSize ] [ -o TimeOut ] [ -P PortNumber ] [ -u AcRegMin ] [ -U AcRegMax ] [ -v AcDirMin ] [ -V AcDirMax ] [ -T AcTimeO ] [ -p NumBiods ] [  -K  {  any  |  2  |  3  } ] [  -k  {  any  |  tcp  |  udp  } ]

Description

The chnfsmnt command changes the mount options of a currently mounted file system. However, before you can change the attributes of a mount, either the /etc/filesystems file must contain an entry for the file system or the file system needs to be currently mounted from an NFS server. This command unmounts the directory, changes the specified options, and mounts the directory with the new options.

Flags

-f PathName Specifies the mount point for the directory.
-d RemoteDirectory Specifies the directory that will be mounted on the path name specified.
-h RemoteHost Specifies the NFS server that is exporting the directory.
-t Specifies whether the directory will be mounted as read-write or read-only.
rw Mounts the directory read-write. This type is the default for the system.
ro Mounts the directory read-only.
-m MountTypeName Corresponds to the type field in the stanza of the entry in the /etc/filesystems file. When the mount -t command MountTypeName is issued, all of the currently unmounted file systems with a field type equal to the string are mounted.
-w { fg | bg } Indicates whether the mount should be attempted in the foreground (fg) or background (bg). If bg is specified and the attempt to mount the directory fails, the mount will be tried again in the background. The fg parameter is the default.
-x Specifies that the server does not support long device numbers.
-X Specifies that the server does support long device numbers. This is the default.
-y Indicates that the execution of suid and sgid programs is not allowed in this file system.
-Y Indicates that the execution of suid and sgid programs are allowed in this file system. This is the default.
-z Indicates that device access through this mount is not allowed.
-Z Indicates that device access through this mount is allowed. This is the default.
-S Makes the mount a soft mount, which means that the system returns an error if the server does not respond.
-H Makes the mount a hard mount, which causes the client to continue trying until the server responds.
-e Prevents keyboard interrupts on hard mounts. This flag is the default.
-E Allows keyboard interrupts on hard mounts.
-a The /etc/filesystems entry for this file system will specify that it should not be automatically mounted at system restart. This is the default.
-A The /etc/filesystems entry for this file system will specify that it should be automatically mounted at system restart.
-s Instructs the mount to use a more secure protocol.
-n Instructs the mount not to use a more secure protocol. This flag is the default.
-I Changes the entry in the /etc/filesystems file but does not remount the directory.
-N Prevents modification of the corresponding entry in the /etc/filesystems file if it exists. If the directory is currently mounted, it is unmounted and then mounted again with the flags and parameters specified.
-B Modifies the entry in the /etc/filesystems file and remounts the file system using the flags and parameters specified. This flag is the default.
-r TimeToRetry Indicates the number of times to retry a mount. The default is 1000.
-b ReadBufferSize Indicates the size of the read buffer in N bytes.
-c WriteBufferSize Indicates the size of the write buffer in N bytes.
-o TimeOut Indicates the length of the NFS time out in N tenths of a second.
-P PortNumber Indicates the IP port number for the server.
-u AcRegMin Holds cached attributes for at least AcRegMin seconds after file modification.
-U AcRegMax Holds cached attributes for no more than AcRegMax seconds after file modification.
-v AcDirMin Holds cached attributes for at least AcDirMin seconds after directory update.
-V AcDirMax Holds cached attributes for no more than AcDirMax seconds after directory update.
-TAcTimeO Sets minimum and maximum time allowed for regular files and directories to AcTimeO seconds. If this option is specified, the other cached attribute times are overridden.
-p NumBiods Specifies the number of biod daemons that are allowed to work on a particular file system. The default is 6.
-k Specifies the transport protocol used for the mount. This flag only applies to AIX Version 4.2.1 or later. Options are:
any
Uses the mount command to select the protocol to use. TCP protocol is the preferred protocol.
tcp
Specifies the TCP protocol.
udp
Specifies the UDP protocol.
-K Specifies the NFS version used for this NFS mount. This flag only applies to AIX Version 4.2.1 or later. Options are:
any
Uses the mount command to determine the correct match, first attempting the highest NFS version available.
2
Specifies NFS Version 2.
3
Specifies NFS Version 3.

Examples

To change a mount to read-only, enter:

chnfsmnt -f /usr/man -d /usr/man -h host1 -t ro

In this example, the chnfsmnt command changes the attributes of the mounted directory to read-only.

Files

/etc/filesystems
                          Lists the remote file systems to be mounted during the system restart.

Related Information

The mknfsmnt command, mount command, rmnfsmnt command.

How to Mount an NFS File Explicitly in AIX Version 4.3 System Management Guide: Communications and Networks.

List of NFS Commands in AIX Version 4.3 System Management Guide: Communications and Networks.

Network File System (NFS) Overview for System Management in AIX Version 4.3 System Management Guide: Communications and Networks.


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