16.4.4. Shell Scripting with guestfish

Once you are familiar with using guestfish interactively, according to your needs, writing shell scripts with it may be useful. The following is a simple shell script to add a new MOTD (message of the day) to a guest:
#!/bin/bash -
 set -e

 guestfish -d "$guestname" -i <<'EOF'
   write /etc/motd "Welcome to Acme Incorporated."
   chmod 0644 /etc/motd