$ Linux Command

Network

exportfs

Maintain the NFS exports table.

nfsexportnetworkfilesystemserver

Additional Notes

exportfs manages the NFS exports table that controls which directories are available to NFS clients and with what options. It reads the /etc/exports file and applies changes to the running kernel's export table without restarting the NFS server.

The command can add, remove, or list exports. It is useful for applying changes to /etc/exports immediately, testing export syntax, and for debugging NFS mount issues. The NFS server daemon (nfsd) checks the export table maintained by exportfs each time a client requests a mount.

Syntax

exportfs [options] [client:path]

Parameters

  • client:path: An export specification in the format hostname:/exported/path. For example, *.example.com:/srv/nfs.

Common Options

  • -a: Export or unexport all directories listed in /etc/exports.
  • -r: Re-export all directories, synchronizing /etc/exports with the kernel's export table.
  • -u: Unexport one or more directories.
  • -v: Verbose output. Show the export options on each line.
  • -i: Ignore /etc/exports and use command-line options and arguments only.
  • -o options: Specify export options directly on the command line (e.g., rw,sync,no_subtree_check).
  • -s: Show the current export list in a format suitable for /etc/exports.
  • -f: Flush the export table completely.
  • --no-can-do: Suppress the "can do" column in the output.

Examples

sudo exportfs -a

Export all directories listed in /etc/exports.

sudo exportfs -r

Re-read /etc/exports and synchronize the kernel's export table.

sudo exportfs -u client:/srv/nfs

Unexport a specific directory from a specific client.

sudo exportfs -v

Show all currently exported directories with their options.

sudo exportfs -o rw,sync,no_subtree_check *:/srv/nfs

Export a directory with specific options without modifying /etc/exports.

sudo exportfs -s

Show the current export list in a format that can be copied into /etc/exports.

Practical Notes

  • Run exportfs -r after editing /etc/exports to apply changes without restarting the NFS server.
  • The client specification can be a hostname, IP address, network wildcard (*.example.com), or CIDR range (192.168.0.0/24).
  • Exports added with -o are not persistent across reboots unless added to /etc/exports.
  • Common export options: rw (read-write), ro (read-only), sync (write changes to disk before replying), no_subtree_check (disable subtree checking for performance), no_root_squash (allow root access on client).
  • Use showmount -e localhost to see what the NFS server is currently exporting.
  • The export table is stored in /var/lib/nfs/etab.