Changing the CPU priority of Mac OS X apps with ‘renice’

Mac’s Activity Monitor app is great, but there’s one thing it can’t do. As a long-time Windows user, I’m accustomed to tweaking the CPU priority on apps that are very CPU-intensive, e.g. compressing video, etc. On Mavericks I’ve noticed a couple of apps tend to slow my system right down (iTunes, Unarchiver, Google Drive), and wanted a quick way to get them under control. So I wrote this shell script.

for APP in iTunes Unarchiver Drive ; do
  PID=`ps -Ac -o pid,command | grep ${APP}$ | awk '{print \$1}'`
  if [ -z $PID ] ; then
    echo \[$APP\] not running
    echo \[$APP\] sudo 20 renice $PID
    sudo renice 20 $PID

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