shell syntax optimized and more options for rebase-vm.sh

roles/lmn_vm/files/rebase-vm.sh

@@ -1,44 +1,79 @@
 #!/usr/bin/bash
-
 # Rebase one level down
-
 set -eu
 
-# if less than one arguments supplied, display usage
-if [  $# -ne 1 ]
-then
-    echo "This script takes as input the name of the VM to rebase one level down"
-    echo "Usage: $0 vm_name"
+show_help() {
+    cat << EOF
+Usage: $(basename "$0") [-n newname] vmname"
+This script takes as input the name of the VM to rebase one level down
+    -n   new name of the rebased image
+EOF
+}
+ 
+while getopts ':n:' OPTION; do
+  case "$OPTION" in
+    n)
+      NEWNAME=$OPTARG
+      ;;
+    ?)
+      show_help
+      exit 1
+      ;;
+  esac
+done
+ 
+shift "$((OPTIND -1))"
+
+# if less or more than one arguments supplied, display usage 
+if [[  $# -ne 1 ]]; then
+    show_help
     exit 1
 fi
 
-VM_NAME=$1
+# change to Images directory
+cd /var/lib/libvirt/images
 
-if [ ! -f $VM_NAME.qcow2 ]
-then
-    echo "File not found $VM_NAME.qcow2"
+VM_NAME="$1"
+
+# check if VM-Diskimage exists
+if [[ ! -f "${VM_NAME}.qcow2" ]]; then
+    echo "File not found ${VM_NAME}.qcow2"
     exit 1
 fi
 
-shopt -s lastpipe
-qemu-img info --backing-chain $VM_NAME.qcow2 | grep image | wc -l | read NUMBASES
-qemu-img info --backing-chain $VM_NAME.qcow2 | grep image | head  -n 3 | tail -n 1 | cut -d' ' -f2 | read NEWBASE
-qemu-img info --backing-chain $VM_NAME.qcow2 | grep image | head  -n 2 | tail -n 1 | cut -d' ' -f2 | read CURRENTBASE
+# check if new VM-Diskimage exists
+if [[ -v NEWNAME ]] && [[ -f "${NEWNAME}.qcow2" ]]; then
+    echo "New Base already exists: ${NEWNAME}.qcow2"
+    exit 1
+fi
 
-if [ ! $NUMBASES -ge 3 ]
-then
+NUMBASES=$(qemu-img info --backing-chain "${VM_NAME}.qcow2" | grep -c image)
+NEWBASE=$(qemu-img info --backing-chain "${VM_NAME}.qcow2" | grep image | head  -n 3 | tail -n 1 | cut -d' ' -f2)
+CURRENTBASE=$(qemu-img info --backing-chain "${VM_NAME}.qcow2" | grep image | head  -n 2 | tail -n 1 | cut -d' ' -f2)
+
+if [[ ! "${NUMBASES}" -ge 3 ]]; then 
     echo "Image must have at least 2 backing-files"
     exit 1
 fi
 
-if [ ! -f $NEWBASE -a -f $CURRENTBASE ]
-then
-    echo "Backingfiles not found $CURRENTBASE, $NEWBASE"
+# check if base Diskimage exists
+if [[ ! -f "${NEWBASE}" ]] || [[ ! -f "${CURRENTBASE}" ]]; then
+    echo "Backingfiles not found ${CURRENTBASE}, ${NEWBASE}"
     exit 1
 fi
 
-qemu-img rebase -f qcow2 -b $NEWBASE -F qcow2 $VM_NAME.qcow2
-rm $CURRENTBASE
-mv $VM_NAME.qcow2 $CURRENTBASE
-chmod a-w $CURRENTBASE
-qemu-img create -f qcow2 -F qcow2 -b $CURRENTBASE $VM_NAME.qcow2
+# rebasing disk image
+qemu-img rebase -f qcow2 -b "${NEWBASE}" -F qcow2 "${VM_NAME}.qcow2"
+if [[ -v NEWNAME ]]; then 
+    # copy and adapt machine definition file
+    CURRENTNAME="${CURRENTBASE/.qcow2/}"
+    cp "xml/${CURRENTNAME}.xml" "xml/${NEWNAME}.xml"
+    sed -i "s/${CURRENTNAME}/${NEWNAME}/" "xml/${NEWNAME}.xml"
+    NEWNAME="${NEWNAME}.qcow2"
+else
+    rm "${CURRENTBASE}"
+    NEWNAME="${CURRENTBASE}"
+fi
+
+mv "${VM_NAME}.qcow2" "${NEWNAME}"
+chmod a-w "${NEWNAME}"