type-fewer-paths-with-brace-expansion.md

Type Fewer Paths With Brace Expansion

Bash has a feature called brace expansion that allows us to do a kind of shorthand when writing out file paths. We can specify multiple variants comma-separated between curly braces and they'll each be expanded into separate arguments.

It's easier to understand this by seeing it. If we type the following (don't hit Enter yet):

$ mkdir src/{one,two,three}

And then hit Tab:

$ mkdir src/one src/two src/three

Bash uses the portion in braces to expand into separate arguments. The part outside the braces gets reused for each. That's where we get some savings from typing out the same path each time.

Here is another example where we use mv to rename a file deeply nested in our project:

$ mv projects/project1/src/app/utils/{names,constants}.js

We don't even have to Tab it out. We can hit Enter directly and mv gets both arguments.

Similarly, how about we change the extension of our renamed file:

$ mv projects/project1/src/app/utils/constants.{js,ts}

I've always found this feature most useful with paths and filenames, but you can do brace expansion with any arguments.

$ echo 1{3,1,6,4,9,2,7,5}
13 11 16 14 19 12 17 15

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