A simple bash script to launch and daemonize QEMU instances

qemu.sh

#!/bin/bash

# daemonize a process by closing its file descriptors and detaching the process
# from its controlling terminal and the current session group
launch_daemon () {
  $1 < /dev/null > /dev/null 2>&1 0<&- 1>&- 2>&-  &
  disown
}

# function to get the array key associated with one value
get_array_key () {
  sed "s/$2//g" <<< $1 | wc -w | tr -d ' '
}

# populates options and qcow2 disk files arrays
opts=()
disk=()

# disks are placed in ~/QEMU/ubuntu-16.04-server/ubuntu-server-16.04.qcow2
for file in $(find ~/QEMU -name "*.qcow2"); do
  opts[${#opts[@]}]=$(basename $(dirname "$file"))
  disk[${#disk[@]}]=$file
done

# select the disk file and run the virtual machine
echo "Select one disk to continue:"
select opt in ${opts[@]}; do
  file=${disk[$(get_array_key "$opts" "$opt")]}
  launch_daemon "qemu-system-x86_64 -m 1024 \
                                    -vga virtio \
                                    -display default,show-cursor=on \
                                    -usb \
                                    -device usb-tablet \
                                    -enable-kvm \
                                    -drive file=$file,if=virtio \
                                    -machine accel=hvf \
                                    -cpu Penryn,kvm=on,vendor=GenuineIntel \
                                    -device e1000,netdev=net0 \
                                    -netdev user,id=net0,hostfwd=tcp::2222-:22"
  exit
done