I first discovered [[fzf]] via a post on hacker news, which demonstrated that in addition to all it’s fuzzy-searching greatness, the output of the fzf could be used as a REPL - instantly running and displaying the output of a command as it’s typed.
The trick is to pipe an empty search into fzf: : | [YOUR_QUERY]. This makes fzf operate only on the query you give it.
Below are a few examples where this behaviour can be used in surprising and effective ways.
Substituting python or ruby in the below command will give you instant REPL output for that programming language.
Ruby:
: | (fzf --multi --preview 'ruby -e {q}' --preview-window=up:70 )
Python:
: | (fzf --multi --preview 'python -c {q}' --preview-window=up:70 )
Use the following to interact with real API responses in realtime, or an a JSON file on disk:
: | fzf --preview 'curl https://jsonplaceholder.typicode.com/posts | jq {q}'
Yes it’s a compiled language, but this can be used for small programs (and it’s pretty cool watching all the compiler messages as you type):
:| fzf --preview 'echo {q} > main.rs && rustc -o main main.rs && ./main'
Try giving it a litle something:
fn main() { println!("Hello, world!"); }
CAUTION needs to be exercised; on every keystroke the command will be executed immediately. If you want a safer version of this, check out Ultimate Plumber, which waits until you press Enter to execute.
So, can fzf be used to execute shell commands, and output the result? Can it help with constructing long bash commands? Yes it can - but you should read the warning above before starting.
Thanks to a commenter on this thread, the below command will cause your chosen shell to instantly evaluate any command you type. For me, this is extremely handy when constructing complicated bash queries using sed/awk etc, as I can previewing the output as I type:
: | fzf --multi --preview='bash -c {q}' --preview-window=up:70
https://github.com/junegunn/fzf