One of the first problems that I came across the Mac was the “File in use” error that occurred whenever I tried to unmount a hard drive, or unmount a USB thumb drive. It was annoying because I didn’t know how to find the source. In Windows, I would face the same problem too, but I had a program that I used to tell me the offending application. It was handy because it would show me what exactly was locking up my file, and I could unlock/remove its hold.

On the Mac, I had to search for something that offered the same functionality, and I found it in the form of a terminal command:

sudo lsof | grep -i

Basically, the command will look for your filename in the list of open processes, and display all relevant information about it on screen. I find this unwieldy though, so I searched around somemore and found a GUI replacement to this terminal command! It’s called What’s Keeping Me, and it does what the terminal command does, except in a pretty GUI.

So now you can find out what’s keeping a file locked on the Mac. Go grab What’s Keeping Me now – it’s donationware, so you can use it for free, and make a donation if you find it useful. Go to the What’s Keeping Me website.