BASH Process Substitution

Today, I learned about shell process substitution from Break on Penguin’s latest video.

Assume you have two files:

$ cat file1
a
b
c

$ cat file2
c
b
a

To see if they are identical when sorted without manually creating your own temporary files, you can:

diff <(sort file1) <(sort file2)

What is happening here?

<() is doing process substitution, which is running the command and then exposing its output as a temporary file.

Super neat!