fixed some commands on Ubuntu guide

Author: sus-admin

_posts/2024-12-11-Cobbler-v3.3.7-Ubuntu-Deployment-Guide.md

@@ -344,7 +344,7 @@ cobbler distro edit --name Ubuntu20-casper-x86_64 --kernel-options 'root=/dev/ra
 create a new autoinstall (`cloud-init`) template from the `cloud-init_user_data` file created above, and configure it as the autoinstallation template for the Ubuntu 20.04 Cobbler PROFILE
 
 ```shell
-sed ':a;N;$!ba;s,      uri: http://\$http_server/cblr/links/\$distro\n#      uri: http://us.archive.ubuntu.com/ubuntu,#      uri: http://\$http_server/cblr/links/\$distro\n      uri: http://us.archive.ubuntu.com/ubuntu,' /var/lib/cobbler/templates/cloud-init_user-data | tee /var/lib/cobbler/templates/Ubuntu20_cloud-init_user-data
+sed -z 's,      uri: http://$http_server/cblr/links/$distro\n#      uri: http://us.archive.ubuntu.com/ubuntu,#      uri: http://$http_server/cblr/links/$distro\n      uri: http://us.archive.ubuntu.com/ubuntu,' /var/lib/cobbler/templates/cloud-init_user-data | tee /var/lib/cobbler/templates/Ubuntu20_cloud-init_user-data
 cobbler profile edit --name Ubuntu20-casper-x86_64 --autoinstall Ubuntu20_cloud-init_user-data
 ```
 
@@ -369,6 +369,8 @@ cobbler sync
 
 The **PXE Client** VM can now be powered on, and should automatically boot to PXE and install Ubuntu 20.04 to the VM HDD using the "Ubuntu20_cloud-init_user-data" preseed template created above.
 
+    - The resulting system will have the `root` super-user account disabled, and will only be accessible with the `ubuntu` user specified in the *cloud-init* config file.
+
 ## Ubuntu 22.04 PXE Deployment
 
 Take similar steps as above to import and automatically deploy Ubuntu 22.04 LTS Server over PXE, using the original `cloud-init_user-data` autoinstall template created above.