How to run copied CLI commands with a leading "$" sign
- Published at
- Updated at
- Reading time
Use at your own risk. 🤓 Before implementing any functionality that makes running copied code easier, be aware that the internet's a bad place. There's always a chance that a command has malicious intent or even includes hidden commands.
I just saw an npm package that makes copying and pasting of shell commands easier. Documented shell commands often include a leading
$ character (e.g.
$ npm install whatever) to signal that the code block is a shell command. And when you're like me, you always copy and paste the
$ sign with the command, leading to a
command not found: $ error in your terminal.
And while it's not a huge deal, you have to either carefully copy the command not to include the
$ sign or paste the command into your terminal and remove the dollar manually. There has to be a better way...
... and that's where the mentioned npm package comes into play. The package provides a global
$ command that behaves like a proxy on your command line. The
$ command simply runs all passed-in arguments.
$ echo "hello world" leads to an executed
echo "hello world".
$ ls is basically the same as
ls. You get the idea. 🙈
This command is one of these tiny adjustments that makes a terminal feel like home. But what if I told you that you can create the same functionality without npm packages or Node.js using two lines of shell scripting? Read on!
Let's start by adding a new shell command to your system. Have a look at your
$PATH configuration. The
$PATH environment variable defines where executable files are located on UNIX systems.
That's the shortened version of my machine's
$ echo $PATH /usr/local/bin:/usr/local/sbin:/Users/stefanjudis/bin:/Users/stefanjudis/.bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
$PATH is a long string that separates all different locations by a
:. And as you see, I have various
bin directories. All my custom commands are placed in my home's
~/stefanjudis/. I chose this location because I don't want to mix system and custom commands (
cat, etc. are located at
Choose a directory to place your new command.
$ pwd /Users/stefanjudis/.bin $ ll .rwxr--r-- 14 stefanjudis 8 Dec 2020 -- $ .rwxr-xr-x 413 stefanjudis 2 Aug 2020 -- git-delete-branch .rwxr-xr-x 183 stefanjudis 19 May 22:03 -- git-pr-select .rwxr-xr-x 538 stefanjudis 17 Dec 2020 -- git-select
Create a new file named
$ in this directory. Yep, that's right, this file doesn't include a file extension or something – it's really just a dollar.
Make sure the file is executable using
chmod 755 $.
If you haven't used the
chmod command before, make sure to read up on "UNIX file permissions".
The file's content is two lines:
#!/bin/zsh exec "$@"
The first line is called a Shebang and defines what program should be used to interpret this file when you run it as a standalone command. In my case, it's the
zsh binary –
#!/bin/bash works fine, too.
exec "$@" runs and expands all the passed-in parameters. And that's all the magic already!
Make sure to include the quotes around
$@ to avoid parameter expansions.
With this one file containing two lines, you can now run
$ echo "hello world" and all these "dollar commands" in your terminal. 🎉
Happy copy and pasting!
Edit: Gonçalo Morais tweaked the
$ script and added a confirmation dialog. Great work!
Thanks to "okdjnfweonfe", Peter Franken and Joe Block for providing some feedback on the initial script. 🙇♂️
Yes? Cool! You might want to check out Web Weekly for more web development articles. The last edition went out 9 days ago.