16.4.5. Augeas and libguestfs Scripting

Combining libguestfs with Augeas can help when writing scripts to manipulate Linux guest virtual machine configuration. For example, the following script uses Augeas to parse the keyboard configuration of a guest virtual machine, and to print out the layout. Note that this example only works with guest virtual machines running Red Hat Enterprise Linux: 
#!/bin/bash -
 set -e
 guestname="$1"

 guestfish -d "$1" -i --ro <<'EOF'
   aug-init / 0
   aug-get /files/etc/sysconfig/keyboard/LAYOUT
 EOF
Augeas can also be used to modify configuration files. You can modify the above script to change the keyboard layout: 
#!/bin/bash -
 set -e
 guestname="$1"

 guestfish -d "$1" -i <<'EOF'
   aug-init / 0
   aug-set /files/etc/sysconfig/keyboard/LAYOUT '"gb"'
   aug-save
 EOF
Note the three changes between the two scripts:
  1. The --ro option has been removed in the second example, giving the ability to write to the guest virtual machine.
  2. The aug-get command has been changed to aug-set to modify the value instead of fetching it. The new value will be "gb" (including the quotes).
  3. The aug-save command is used here so Augeas will write the changes out to disk.

Note

More information about Augeas can be found on the website http://augeas.net.
guestfish can do much more than we can cover in this introductory document. For example, creating disk images from scratch: 
guestfish -N fs
Or copying out whole directories from a disk image: 
><fs> copy-out /home /tmp/home
For more information see the man page guestfish(1).