Linux @lemmy.ml 𞋴𝛂𝛋𝛆 @lemmy.world 3w ago

Is there an easy way to filter all terminal commands that contain a --help flag?

Or is there maybe a way to set the pager for all help related queries to some command? I'm using bat and would like to pipe all --help through | bat --language=help by default for the syntax highlighting and colored output... Or if you know a lower effort way to color the output of --help let me know.

23 comments

I think your best bet to to create a script called help and run "help <command>" and the script would do the rest.
- I think this is the correct answer in all honesty. Create a new script like help (or man2 or whatever) that pipes the argument through bat for you.
- There has to be a hook somewhere for every command that executes. I'm not sure, but something in the chain after using set -x then running any terminal command likely is on the right path to doing this. (If you try set -x, you can turn it off with set +x). set -o options are another I'm not very familiar with but might be related.
  
  set -x configures the running process, your shell. This is a posix standard flag. See https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
  
  there has to be a hook somewhere for every command that executes
  
  Why do think this? I'm not aware of any shells that have such a feature. I'm not saying it couldn't be done, but it would be a new feature.
  
  I like the other suggestion of having a wrapper script that does what you need.
  
  You'd be intercepting all commands just to verify if they have a help flag and then if not executing them as they were intended. If the intercept got broke, then the shell would be completely broken.
To answer the original question, even though @RedWeasel@lemmy.world’s advice really is superior:

All commands that can be executed via your shell must live in your $PATH or their subdirectories. You could enumerate all files in there, filter by being executable, and run them with the --help argument.

You can then filter these commands by their exit code. If --help is a recognized flag, the exit code should be 0. Otherwise it should be something else. (Running every command blindly might be a bad idea though.)
- Or if you are lazy you could add "-h" as an option to said help command for when --help doesn't work. Shouldn't take to long to to make a list with a script that runs each command to with --help and logs it all to a file though. Then just go look for the ones that don't like it in the log. Apparently bash has a builtin command named help, so a different name is probably better then.
  
  ls -1 $dir | while read line do echo "----------" $line --help |& >> logfile.txt done
  
  Just search in you favorite pager for "-----" and just hit "next" key.
There's no particularly smart way to accomplish this in the exact way that you want. I don't like the solution which searches your $PATH because now you're adding latency to search your entire $PATH for every command to add this functionality. It's a singularly better solution to tell the CLI what you want versus the CLI attempting (using logic) to figure it out.

The easiest solution here is to create your own command which calls the target application with --help;

#!/bin/bash $1 --help | bat --language=help

Then run it;

$ script_name docker

and it will run docker --help | bat --language=help. If you use this solution a lot you can try to use bash function which you call at the end of commands if they error;

helpfunc() { $1 --help | bat --language=help } trap 'helpfunc' ERR

But now you have to run logic to truncate previous commands to only return the first word of a command from history and it becomes a real PITA...

Long story short, if you want to hack your console experience like this, you're looking for a functional shell scripting language, like Elvish shell and not bash.
cd into the directory you want to test commands.

bash

for i in ls

do

$i --help >/dev/null 2>&1 && echo $i

done

any command which honors a --help will get listed. I suppose you could add a >> /tmp/output after the echo $i to log it. run it in /bin, /usr/bin, usr/local/bin

ah ...and that ls in the commands listed above is a backtick ls backtick. backtick is the key in the upper left hand corner of the keyboard which shares a key with ~
Grep?

23 comments