nfsref(8)

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2NFSREF(8)                   System Manager's Manual                  NFSREF(8)
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NAME

7       nfsref - manage NFS referrals
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SYNOPSIS

10       nfsref [-?d] [-t type] add pathname server export [ server export ... ]
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12       nfsref [-?d] [-t type] remove pathname
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14       nfsref [-?d] [-t type] lookup pathname
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INTRODUCTION

17       NFS  version  4 introduces the concept of file system referrals to NFS.
18       A file system referral is like a symbolic link  on  a  file  server  to
19       another  file system share, possibly on another file server.  On an NFS
20       client, a referral behaves like an automounted directory.  The  client,
21       under  the  server's  direction,  mounts a new NFS export automatically
22       when an application first accesses that directory.
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24       Referrals are typically used to construct  a  single  file  name  space
25       across  multiple  file servers.  Because file servers control the shape
26       of the name space, no client configuration is required, and all clients
27       see the same referral information.
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29       The  Linux NFS server supports NFS version 4 referrals.  Administrators
30       can specify the refer= export option in  /etc/exports  to  configure  a
31       list  of  exports from which the client can choose.  See exports(5) for
32       details.
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DESCRIPTION

35       The nfsref(8) command is a simple way to get started managing  junction
36       metadata.  Other administrative commands provide richer access to junc‐
37       tion information.
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39   Subcommands
40       Valid nfsref(8) subcommands are:
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42       add    Adds junction information to the directory  named  by  pathname.
43              The  named  directory  must  already exist, and must not already
44              contain junction information.  Regular  directory  contents  are
45              obscured to NFS clients by this operation.
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47              A  list of one or more file server and export path pairs is also
48              specified on the command line.  When creating an NFS basic junc‐
49              tion, this list is stored in an extended attribute of the direc‐
50              tory.
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52              If  junction  creation  is  successful,  the  nfsref(8)  command
53              flushes  the  kernel's  export cache to remove previously cached
54              junction information.
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56       remove Removes junction information from the directory named  by  path‐
57              name.  The named directory must exist, and must contain junction
58              information.  Regular directory contents are made visible to NFS
59              clients again by this operation.
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61              If  junction  deletion  is  successful,  the  nfsref(8)  command
62              flushes the kernel's export cache to  remove  previously  cached
63              junction information.
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65       lookup Displays  junction  information stored in the directory named by
66              pathname.  The named directory  must  exist,  and  must  contain
67              junction information.
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69              When  looking up an NFS basic junction, the junction information
70              in the directory is listed on stdout.
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72   Command line options
73       -d, --debug
74              Enables debugging messages during operation.
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76       -t, --type=junction-type
77              Specifies the junction type for the operation.  Valid values for
78              junction-type are nfs-basic or nfs-fedfs.
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80              For  the add subcommand, the default value if this option is not
81              specified is nfs-basic.  For the remove and lookup  subcommands,
82              the  --type option is not required.  The nfsref(8) command oper‐
83              ates on whatever junction contents are available.
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EXAMPLES

86       Suppose you have  two  file  servers,  top.example.net  and  home.exam‐
87       ple.net.  You want all your clients to mount top.example.net:/ and then
88       see the files under home.example.net:/ automatically in top:/home.
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90       On top.example.net, you might issue this command as root:
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92              # mkdir /home
93              # nfsref --type=nfs-basic add /home home.example.net /
94              Created junction /home.
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FILES

98       /etc/exports
99              NFS server export table
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AUTHOR

107       Chuck Lever <chuck.lever@oracle.com>
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111                                  9 Jan 2018                         NFSREF(8)