Backing up your Homebrew packages

Update: while this is a good template to do a quick backup, a more flexible solution exists in the Brew Bundle project. Thanks @MacHomebrew for the pointer!

It’s a good idea to keep track of what packages you’ve got installed in Homebrew - good for provisioning a new Mac, good for recovering from a disaster.

To get a list of the current packages is as simple as

brew ls

but that gives us everything, dependencies and all. If we just want what we explicitly installed, we should go for

brew leaves

like the leaves of our dependency tree.

Just pipe that out into a file

brew leaves > homebrew-packages.txt

for safekeeping and get it under version control along with the rest of you configuration files.

When it comes to recovery, we can save time and effort by using xargs to pipe out each of the lines as an argument to brew install

cat homebrew-packages.txt | xargs brew install

and everything will (re)install in one go. It may take some time.

Maybe you want to add to the list from one machine without overwriting the current list? I just did (for one reason or another), and it’s fairly easy to handle. Instead of overwriting the text file, append to the end of it

brew leaves >> homebrew-packages.txt

Now you might have some repetitions in that file - get rid of them with

sort homebrew-packages.txt | uniq

This sorts the original list into order, then removes any lines that are repetitions of the one before, leaving only one. Pipe that out to a new file

sort homebrew-packages.txt | uniq > homebrew-packages-reconciled.txt

and overwrite the old one if you need to (just don’t do it in the pipe - it doesn’t like it and the file becomes blank. Boo.)

Did I mention that Text Processing with Ruby was an amazing book? I worked out how to do the above from what I read in the section on Unix tools. Nice.