List all existing program paths from your Bash's history. (Bash One Liner)
from thingsiplay@beehaw.org to linux@lemmy.ml on 15 Jun 09:04
https://beehaw.org/post/20584479

It only works with the first command in the recorded history, not with any sub shells or chained commands.

#!/usr/bin/env bash

# 1. history and $HISTFILE do not work in scripts. Therefore cat with a direct
#    path is needed.
# 2. awk gets the first part of the command name.
# 3. List is then sorted and duplicate entries are removed.
# 4. type -P will expand command names to paths, similar to which. But it will
#    also expand aliases and functions.
# 5. Final output is then sorted again.

type -P $(cat ~/.bash_history | awk '{print $1}' | sort | uniq) | sort

After reading a blog post, I had this script in mind to see if its possible. This is just for fun and I don’t have an actual use for it. Maybe some parts of it might inspire you to do something too. So have fun.

Edit 1:

After some suggestions from the comments, here is a little shorter version. sort | uniq can be replaced by sort -u, as the output of them should be identical in this case (in certain circumstances they can have different effect!). Also someone pointed out my useless cat, as the file can be used directly with awk. And for good reason. :D Enjoy, and thanks for all.

type -P $(awk '{print $1}' ~/.bash_history | sort -u) | sort

I still have no real use case for this one liner, its mainly just for fun.

#linux

threaded - newest

hexagonwin@lemmy.sdf.org on 15 Jun 11:56 next collapse

sort | uniq can be sort -u instead btw

thingsiplay@beehaw.org on 15 Jun 12:35 collapse

They are not exactly the same. I always default to piping it, because I never remember which to use when. And had to lookup again to make sure I was not hallucinating: unix.stackexchange.com/questions/76049/…/76095#76…

hexagonwin@lemmy.sdf.org on 15 Jun 12:48 next collapse

Interesting, I never knew. Thanks

non_burglar@lemmy.world on 15 Jun 13:58 collapse

I agree they aren’t the same, especially if you need uniq to count things.

However, be aware that pipes can be a real problem in scripts because of globbing and expansion.

just_another_person@lemmy.world on 15 Jun 12:45 next collapse

Or just use zsh 🫰

lauha@lemmy.one on 15 Jun 13:59 next collapse

Can this one liner determine if program halts too?

thingsiplay@beehaw.org on 15 Jun 14:02 next collapse

I’m actually not sure what you mean by that. This script will only list the programs you used in the terminal. It prints the fullpath of each command. That’s all it does.

Do you want know if a program is currently running?

lauha@lemmy.one on 15 Jun 14:44 collapse

Silly me misunderstood the intention of the script. I imagined it lists the programmatic paths the program can take, like all the decision in the program. :)

TechieDamien@lemmy.ml on 16 Jun 06:09 collapse

That’s impossible, look up the Halting problem

lauha@lemmy.one on 16 Jun 10:49 collapse

That’s the joke

pemptago@lemmy.ml on 15 Jun 21:12 collapse

As I’ve been working on an install script for making my setup more portable, this is handy and timely. Thanks for sharing!

PS I hate to be the UUOC person. I’m sure you’re already aware and it was a deliberate choice.

thingsiplay@beehaw.org on 15 Jun 21:29 collapse

PS I hate to be the UUOC person. I’m sure you’re already aware and it was a deliberate choice.

I wish it was. I honestly forgot. yeah, shame on me. :D Before this, at the position of cat there was actually a different command, which I replaced with this. And I didn’t think of adding the file to awk instead. I’ll update the line with this suggestion and a suggestion from someone else.