Housekeeping

- Update README
- Run shellcheck on .sh files
- Add helper scripts
- Remove eirene vm variant
- Add post-install checklist

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/system/scripts/cleanup/cleanup.sh

@@ -1,4 +1,4 @@
-if [ "$(id -u)" -ne 0 ]; then
+if [[ "$(id -u)" -ne 0 ]]; then
   echo "This script must be run as root or with sudo privileges."
   exit 1
 fi
@@ -6,12 +6,12 @@ fi
 delete_subvolume_recursively() {
   IFS=$'\n'
   for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
-    delete_subvolume_recursively "/mnt/btrfs/$i"
+    delete_subvolume_recursively "/mnt/btrfs/${i}"
   done
   btrfs subvolume delete "$1"
 }
 
-if [[ -e /mnt/btrfs && $(mountpoint -q /mnt/btrfs) ]]; then
+if [[ -e /mnt/btrfs && -n $(mountpoint -q /mnt/btrfs) ]]; then
   echo "/mnt/btrfs is already mounted. Exiting."
   exit 1
 fi
@@ -20,9 +20,9 @@ mkdir -p /mnt/btrfs
 mount /dev/mapper/luks /mnt/btrfs
 
 if [[ -e /mnt/btrfs/@.bak ]]; then
-  if [ "$(ls -A /mnt/btrfs/@.bak)" ]; then
+  if [[ -n "$(ls -A /mnt/btrfs/@.bak)" ]]; then
     for i in /mnt/btrfs/@.bak/*; do
-      delete_subvolume_recursively "$i"
+      delete_subvolume_recursively "${i}"
     done
   else
     echo "/mnt/btrfs/@.bak is empty. Nothing to delete."