A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

I have seen this error when my Mac has auto rebooted for some reason. Firefox does not show up as a running process and can’t be found using the Force Quit… feature so what to do? It’s time to drop into a terminal session to go looking for a rogue child process that is keeping Firefox from opening.

(⎈ default)➜  ~ ps -ax | grep fire
1820 ??       312:27.66 /Applications/Firefox.app/Contents/MacOS/firefox

There is the culprit and it needs to be killed

(⎈ default)➜  ~ kill -9 1820

Firefox should now launch without an issue. If for some reason that doesn’t get it done there are two alternative things to try:

• delete the .parentlock file

• delete an unknown identity

To delete an unknown identity run the following command at a terminal session

(⎈ default)➜  ~ /Applications/Firefox.app/Contents/MacOS/firefox-bin -P

You should see a popup window that displays the identities known to Firefox. Delete the one(s) you didn’t create and restart Firefox.

Failed to run protoc

Doing some grpc work this weekend and ran into this error

failed to run protoc: exit status 1: protoc-gen-go-grpc: program not found or is not executable

Tried running an update to no avail thusly

go get -u github.com/golang/protobuf/protoc-gen-go

Finally solved it by running this

go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

brew cask commands don't function because a package has a broken header

I was getting the follow error when running brew upgrade or cask commands

Error: Cask 'haskell-for-mac' is unreadable: undefined method `dots_to_slashes' for "1473.1526101439":Cask::DSL::Version

After running brew uninstall, brew purge, brew doctor and having no luck resolving the issue I headed over to

/usr/local/Caskroom

and then just did

rm -rf haskell-for-mac

Problem solved - not what I would have expected but it worked.