I just came up with this idea of abusing fzf --preview flag to turn simple commands into live REPL with instant feedback loop - GitHub repo

Examples

Live awk preview

$ echo '' | fzf --print-query --preview 'echo "a

b

c

d" | awk {q}'

Live awk preview

Peek into contents of a directory

$ echo '' | fzf --preview 'ls {q}'

fzf + ls

Execute a Ruby script

$ echo '' | fzf --print-query --preview 'ruby -e {q}'

fzf + Ruby

I have many more ideas for these. For now I only made 3 because I wanted to release this ASAP. If you like it, please check the repo which will be updated regularly here. Also, feel free to contribute your own ideas.

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