QEMU Convert Script

stacksofplates

QEMU doesn't preallocate QCOW2 images by default. If you want to preallocate you have to either convert an existing disk or preallocate at creation. I'm lazy and get tired of typing

qemu-img convert -f qcow2 -O qcow2 -o preallocation=metadata disk1.qcow2 disk2.qcow2

So I wrote a script where I can just type

convert disk1.qcow2 disk2.qcow2

It does some basic error handling, like if the disk you are converting doesn't exist it lets you know, and if you are trying to convert to a file that already exists it lets you know.

I also gave it an interactive mode with -i so it will ask you what the disks are (just for fun).

#!/bin/bash

#Script to convert qemu-images with preallocation

#Script functions
function script_help () {
  echo "
      Usage: $(basename $0) [options] original-file new-file

          -i   Ineractive mode

          -h   this help text

          original-file  File to convert

          new-file       File to create

      Example:
        $(basename $0) file.raw new-file.qcow2"

  exit ${1:-0}
}

function interactive_convert_file () {

  echo "Original file"
  read originalFile

  if [[ ! -f $originalFile ]]; then
    echo "File $originalFile not found"
    exit 1
  fi

  echo "File to convert to"
  read newFile

  if [[ -e $newFile ]]; then
    echo "File already exists!"
    exit 1
  fi


  qemu-img convert -f qcow2 -O qcow2 -o preallocation=metadata $originalFile $newFile

  exit ${1:-0}

}

function argument_convert_file () {

  if [[ ! -f $origFile ]]; then
    echo "File $origFile not found"
    exit 1
  fi

  if [[ -e $newFile ]]; then
    echo "File $newFile already exists!"
    exit 1
  fi

  qemu-img convert -f qcow2 -O qcow2 -o preallocation=metadata $origFile $newFile

  exit ${1:-0}

}

#Show help if no arguments or options are passed
[[ ! "$*" ]] && script_help 1
OPTIND=1


#Read command line options
while getopts "ih" opt; do
    case "$opt" in
      i) interactive_convert_file ;;
      h) script_help ;;
      \?) script_help 1 ;;
    esac
done
shift $(($OPTIND-1));

#Run argument function
origFile=$1
newFile=$2
argument_convert_file