Run any command adb provides on all your currently connected devices. Credit: http://stackoverflow.com/a/17882578

adb+

#!/bin/bash
# Script adb+
# Usage
# You can run any command adb provides on all your currently connected devices
# ./adb+ <command> is the equivalent of ./adb -s <serial number> <command>
adb devices | while read line
do
  if [ ! "$line" = "" ] && [ `echo $line | awk '{print $2}'` = "device" ]
  then
      device=`echo $line | awk '{print $1}'`
      echo "adb -s $device $@ ..."
      adb -s $device $@
  fi
done