Bang Shortcuts

Brian Hicks, December 8, 2020

Another you-get-to-join-the-lucky-ten-thousand post here!

There are a bunch of shortcuts involving exclamation marks that shells will automatically expand. There are so many things you can do with these! (See the "History Expansion" section of the Bash manual page) I just want to highlight a few of the ones I use every day:

• !! expands to the same command you just typed. For example, entering !! will just re-run your last command. You can use this to fix goof-ups. For example, sudo !! will re-run the last command with sudo prepended. Perfect for when you apt-get install something as your login user instead of root.

• !$ expands to the last argument of the last command I mostly use this to perform several operations on the same file. For example, I mv config/database.yml.sample config/database.yml, then kak !$ to edit it to customize. I also use this frequently to preview something that I've just generated. For example, make dist/index.json and then less !$ (or jq . !$ to pretty-print JSON!)

• !* expands to all the arguments of the last command I don't use this one as much, but it's helpful when I misspell a command. For example, I use a tool called aide at work. I often misspell it (e.g. aid build monolith), say "ah shoot, again?" and then correct with aide !*.

Some shells (ZSH at least) will automatically expand these for you if you hit tab after typing them so you can see what you're in for before you commit.