Quick Tip

Unleash `diff` with Process Substitution for Inline Comparisons

Challenge: You need to compare two files or command outputs side-by-side within a single terminal window or a script, and a simple `diff` might not be the most visually intuitive way to do it, especially when dealing with dynamically generated content.

The Solution: Utilize Bash’s process substitution with the `diff` command to create temporary, on-the-fly file-like objects for comparison.

diff <(command1) <(command2)

Why it works: Process substitution (`<(…)`) allows a command’s output to be treated as if it were a file, enabling `diff` to compare the output of two commands directly without needing to save them to temporary files first.

Pro-Tip: You can also use this to compare a file with command output: diff my_file.txt <(some_command)

Linux Tips & Tricks | © ngelinux.com | 5/13/2026