If you’re a dev who is new to the terminal, or rarely uses it, you probably don’t know much the shell’s history and how to use it to your advantage.
Time to change that by teaching you some tricks I use everyday.
Hit ⌃+R to search the history
Hey you, the dev hitting the ↑ (Up Arrow) key a hundred times to search for a command you typed yesterday, stop that. You’re just wasting your time!
Instead, hit ⌃ (Ctrl) + R and type keywords to search your history. (And nope, it’s not ⌘ [Cmd] on macOS—it’s still ⌃.) It’s your terminal’s time machine.
The more you use it, the faster it’ll be engrained in your muscle memory to the point you’ll never think of hitting ↑ anymore. Instead, let’s say you’re looking for the last ls command you typed, you’ll hit ⌃+R then ls and you’ll find it right away.
The command history is a feature found in most shells enabled by default, including Zsh and Bash.
Command notes with #
You typed a long complex command, maybe one that uses sed or awk or grep. You’d like to save it for later, but since it’s using a program you use often, you’re worried searching for it with ⌃+R won’t be enough to find it. You’ve probably did many trials and errors to come up with the correct command, and you don’t want to lose it and have to go through the process again.
Here’s one thing you can do to help yourself. Once you’ve typed the correct command you want to save, add a comment at the end:
echo hello-world | sed -E 's/-/_/g' # Convert all dashes to underscores
Like in shell scripts, the part of every line starting with a #—which is prefixed by a space if it’s not the first character of that line—is ignored. Meaning the above adds a comment to a command, like a note, which will be saved in history and is searching later. If you type the example above and do Ctrl+R then type “underscore,” that command will show up again. That’s much easier to find than having to go through a hundreds of sed commands you’ve tested before it.
Prepare a command for later
Extending the comment tip above, there are times you are writing a long command with dozens of arguments, but then you need to clear it because you just realised you need to run something else first. However, you don’t want to lose what you just wrote!
You may copy and paste the command out of your terminal into a text file or something. But there’s a simpler way.
Just go back to the beginning of the line, add a #, to turn the whole line into a comment that will be remembered—and be searchable—in your history:
# ffmpeg -i input.mp4 -filter:v "crop=in_w:in_h-50,crop=ceil(in_w/2)*2:ceil(in_w/16*9/2)*2"
# ^ The `#` in front saves the command as a comment in the history.
When you want to use that command, search for it with ⌃+R, go back to the beginning of the line, and remove the # and any leading space—because if you keep the space in, remember, the command will be excluded from the history—then run it!
Repeat the last command with !!
Sometimes you wrote a long complicated command, but then you need to run it one more time with an extra argument or with sudo. Instead of searching for the command in the history and edit it, simply use !!. That will get replaced by the previous command you ran:
vim /etc/hosts
sudo !! # Run the last command, `vim /etc/hosts`, with sudo.
bundle show sinatra
cd `!!` # Run `bundle show sinatra` again, but use its output with `cd`.
Bonus: For repeating the same command with sudo, you may also want to look into plugins available for your shell. For example, the sudo plugin for Oh My Zsh lets you hit Esc to repeat the last command with sudo.
Exclude from history with a space
Keeping your commands in a history forever is great for later reference, but what if there are commands you don’t want to save? Maybe you’re inputting a command that has a secret key in it or some private details.
Simple. Prefix your command with a blank space. If a line begins with a space (), it will act like your prompt’s incognito mode and will not save the command in history:
# Command saved in history
echo "I'm in your history"
# Command not saved in history
echo "I'm not in your history"
# ^ Notice the blank space at the beginning.
However, that behaviour is