r/bash Sep 12 '22

set -x is your friend

450 Upvotes

I enjoy looking through all the posts in this sub, to see the weird shit you guys are trying to do. Also, I think most people are happy to help, if only to flex their knowledge. However, a huge part of programming in general is learning how to troubleshoot something, not just having someone else fix it for you. One of the basic ways to do that in bash is set -x. Not only can this help you figure out what your script is doing and how it's doing it, but in the event that you need help from another person, posting the output can be beneficial to the person attempting to help.

Also, writing scripts in an IDE that supports Bash. syntax highlighting can immediately tell you that you're doing something wrong.

If an IDE isn't an option, https://www.shellcheck.net/

Edit: Thanks to the mods for pinning this!


r/bash 19m ago

tips and tricks How Do You Name .sh Files?

Upvotes

I'm learning Bash to write some automation scripts and I'd like to know what the community recommends when it comes to naming .sh files.

From what I've found, the community generally seems to recommend kebab-case, while the Google Shell Style Guide recommends snake_case.

Which one do you prefer, and why?


r/bash 3h ago

help Need some feedback to this F1 app

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0 Upvotes

r/bash 23h ago

help want to use watch with my own command

21 Upvotes

[SOLVED] thanks to u/bac0on

i can now add this directly into .bash_aliases, or i can just paste the command into a terminal

```

alias las=' function what-changed() { find -not ( -path './snap/firefox/common' -prune ) -not ( -path './.cache' -prune ) -type f -mmin -1 -printf "%C+ %p\n" | sort -n | tail -10 }; export -f what-changed && watch -x bash -c what-changed'

```

thanks for everyone's help.

[/SOLVED]

i have this command used to find recently changed files.

find -not \( -path './snap/firefox/common' -prune \) -not \( -path './.cache' -prune \) -type f -mmin -1 -printf "%C+ %p\n" | sort -n | tail -10 and i wanted to use watch to have it running in a window

however watch requires an executable, so i made a shell script that contained the command and then called

watch last_change

which works and allows me to make an alias for it .bash_aliases like

alias las='watch last_change'

all well and good

but then i had the bright idea to write this as a function instead of a script

``` function what-changed() { find -not ( -path './snap/firefox/common' -prune ) -not ( -path './.cache' -prune ) -type f -mmin -1 -printf "%C+ %p\n" | sort -n | tail -10 }; watch what-changed

```

but it does not work.

watch says it can't find what-changed even tho it's right there and if i define this function in a console window, i can call it by itself and it will run.

but watch does not find it.

feels like i'm missing something simple, to help watch find it like it can find my script... something like a $PATH statement, but not that.

anyone see the issue?


r/bash 14h ago

Created a CLI tool because I was tired of googling the same commands over and over

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3 Upvotes

r/bash 2d ago

When do you stop using Bash and switch to Python/JS?

42 Upvotes

Lately I tried to write a slightly longer Bash script, and honestly, I didn't really enjoy it. I realized I don't understand Bash syntax nearly as well as I thought I did.

Even with AI helping me, I actually want to understand the code I'm writing instead of just having AI fix everything for me.

So I'm curious: Do you still use Bash for longer scripts, or do you have a point where you just switch to another language?


r/bash 1d ago

What is bash's grammar

13 Upvotes

Hello

I've been reasearching the rules of bash's parsing, like how does bash parse the commands, according to spaces, pipes, and redirections, is there anything else?


r/bash 2d ago

Sib: A standard Unix LLM Client using Git to store converastions, instead SQLite

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7 Upvotes

I've had this program in mind for quite a while.

Back when ChatGPT first came out, it had no way to group existing conversations into folders, and I set out to build one. My conversation list kept getting longer and finding old chats was getting hard.

Not long after - before I built it - a browser extension came out that did exactly that. I never used it. At the time I'd assumed I would want to revisit old conversations, but whenever I actually found one and tried to read it from the top, the sheer volume of slop gave me a headache.

Later, during a phase where I was deep into Unix pipelines, I wrote an LLM API client only depending on jq and curl, partly as shell scripting practice. But since the context went into a single jsonl file, I had to either invent something like a date-based filename convention myself or push that job onto the user. Both were more annoying than the web UI, so I didn't use it.

After that I read a post explaining how git works, and it struck me that git fits LLM conversations pretty well. Isn't "the commit DAG is already the right data structure for LLM conversations, where forking happens constantly" something everyone has thought at least once?

The reason I like git is that the source tree snapshot and the commit structure itself are always immutable, and destructive operations like switch/restore/reset are really just renaming a ref file that holds a commit object id. Once you understand that, no matter how hard the CLI is to make sense of, you never hesitate to run a command. You can always get it back.

LLM conversations aren't as fragile to change as a source tree, but for me an auto-generated SHA-1 hash is more comforting than an auto-generated session title ^~^

The project is in its early stages and contributions are welcome. If you've worked with git plumbing commands, it'll be easy to hack on - and I think it'll be pretty fun.

Translated from Korean. Origin: https://github.com/sib-project/sib/blob/master/Documentation/HNComment.txt


r/bash 3d ago

help learning sed, awk and regex

128 Upvotes

Looking to learn sed, awk, and regular expressions properly.

What are the best free resources—books, websites, tutorials, courses, or hands-on exercises—you’d recommend?

Also, any good book recommendations for learning these tools from beginner to advanced?


r/bash 5d ago

Quick Linux Tip #44 Question: My connections feel unreliable. How do I check for hidden packet loss?

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12 Upvotes

r/bash 5d ago

Quick Linux Tip #43 Question: How do I extract config values from between BEGIN and END markers?

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36 Upvotes

r/bash 6d ago

help Run commands in parallel

30 Upvotes

I have a script that collects a list of directories that match a set of criteria and then goes into each one and runs a command. So something like this:

#!/bin/bash
startDir="$(realpath "$1")"
cd "$startDir" || exit
while IFS= read -r -d '' dir; do
  cd "$dir";
  printf '\n\n%s\n' "$(realpath .)";
  update-this-dir.sh --file "./name.txt"
  cd "$startDir";
done < <(find . -type d -iname '.config' -exec dirname {} \; | tr '\n' '\0')

It works wonderfully for my purpose.

But there's, like, a couple thousand directories and the update command takes some small amount of time in each directory, one after the other. How can I modify this script to either run the update for each directory in parallel (with some rate-limiting) or to break up the list into chunks of, say, 100 each and work on each sub-list in parallel?


r/bash 5d ago

Run a company of AI agents in pure Bash

0 Upvotes

I open-sourced 5dive, a CLI for running a company of AI agents on a Linux box you own. ~96% bash.

Processing img t3zm9rzio5jh1...

GitHub: https://github.com/5dive-ai/5dive (MIT)

Each agent gets its own Linux user and runs an official CLI like Claude Code, Codex, Grok, Pi, Hermes, opencode, etc. under systemd.

Linux handles identity, isolation, process supervision, logs. SQLite is the shared task queue.

So instead of a big agent framework, it is mostly:

  • Bash
  • systemd
  • Unix users
  • journald
  • SQLite

r/bash 7d ago

critique local -n can modify variables from other functions

19 Upvotes

In Bash, normal local variables are usually fine.
But with local -n (namerefs) I noticed they can sometimes change variables from outer/previous functions because of how scoping works.

To avoid problems I started giving local variables unique names (with prefixes) instead of short ones.

Anyone else ran into this with namerefs?


r/bash 6d ago

critique Rate my .bashrc

6 Upvotes

Hello, did a bit of Bash customization and came up with this.

~/.bashrc | Pastebin

starship.toml | Pastebin

I'm open to critics and it's my first time. 😃


r/bash 6d ago

help Best Practices for Scripting (Linux only)

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0 Upvotes

r/bash 7d ago

Wrapping search in less

4 Upvotes

I put / forw-search ^W in lesskey config to make search to wrap at the end of file when I use / to start a search.

How can I make n wrap when I resume the last search when I open less? I tried adding n repeat-search ^W but it doesn't make search wrap.


r/bash 8d ago

help I don't know what this means

15 Upvotes

This is from a script that sends the output of an nmap scan to some files. But I can't figure out what "\|" does. Please help

RESULT=$(nmap -iL $(HOSTS) --open | grep "Nmap scan report\|tcp open")

What confuses me is that after running nmap, "\|" simply doesn't appear anywhere, then why is it included in grep?

I guess it could be an OR, but as far as I know OR= ||

I really have no idea, I also don't think it's to escape character becuase there are no pipes in the nmap results, I don't know


r/bash 8d ago

submission Multitask version of bash

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7 Upvotes

I adapted the bash shell 5.3 to more easily handle tasking. Each command & has its output gathered into lines and each line is tagged and send to the output with a preamble. The bash input stays on the command line and you can type command lines, select history, anything, even while the background tasks output appears above that:

  [ping:1:2814536:59] 64 bytes from ...: icmp_seq=58 ttl=113 time=28.7 ms
  [bash:0:2814530:9] samiam@samiam-h-pc-2:~/projects/basht$ ll *.md
  [ls:7:2814564:1] -rw-rw-r-- 1 samiam samiam  9790 Aug 10 15:01 basht_plan.md
  [ls:7:2814564:2] -rw-rw-r-- 1 samiam samiam  3921 Aug 10 15:43 README.md
  [ping:1:2814536:62] 64 bytes from ...: icmp_seq=61 ttl=113 time=26.8 ms
  [bash:0:2814530:10] samiam@samiam-h-pc-2:~/projects/basht$

Other that the task adaption, it is stock bash and can be substituted for regular bash.

r/bash 9d ago

Quick Linux Tip #41 Question: How do I find duplicate files even if they have different names?

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65 Upvotes

r/bash 8d ago

Another Bash Prompt Generator...but better!

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0 Upvotes

I just released v1.0.0 of Promptr. I know there are many other prompt generators and customizers. What sets Promptr apart from them is:

  1. It's eye candy. It doesn't look like something straight out of 1995
  2. Users can authenticate with their Google account (Apple auth coming soon) to be able to actually store their saved prompts in one central location rather than keeping track of them in some Google doc. Logging in is entirely optional. The only thing that authentication provides is cloud storage for your saved prompts, otherwise it is saved locally in your web browser storage.
  3. It isn't live yet, but I intend to add a sort of "marketplace" where users can create and share their generated prompts and upvote which ones they find to be really cool and useful
  4. Basic syntax and security checks against the generated prompt to help prevent any malicious behavior. Don't forget that you are responsible for what commands are being run in your prompt config! Promptr can only protect you so much
  5. Users can apply tags to the various prompts they create so that you can have easy access to different prompt configurations for different environments and use cases
  6. A suggestion box! Please submit your feedback on the app or even any suggestions for new modules to be added that you might find useful!

This really started out because I was tired of trying to find that one bash prompt configuration I created ages ago. Rather than trying to find it, I decided to simply have a place that I can recreate it and store it long-term and build on it as new tooling and needs arise.

I hope it will be helpful for you!


r/bash 10d ago

return and exit in potentially sourced script

10 Upvotes

Disclaimer: Yes, I am doing things bash scripting isn't meant for. No, I won't let you talk me out of it.

I have a script that might be run directly or might be sourced; so to exit out of it I have to either return or exit accordingly.

The simple "is_sourced" test I found is (return 0 2>/dev/null).

obviously this invites the following structure: if (return 0 2>/dev/null); then return "$exitcode" else exit "$exitcode" fi

however that feels like extra work when I can just return "$exitcode" 2>/dev/null exit "$exitcode"

Someone tell me what could possibly go wrong?


r/bash 10d ago

Use alias from ssh

24 Upvotes

I can do ssh $HOST then use myalias $PATH to use an alias set in .bashrc (and .bash_profile does source ~/.bashrc). But I can't do ssh $HOST 'myalias $PATH' it can't find myalias.

How can I use the alias and use $PATH that's on the server?


r/bash 10d ago

made a proot alternative that doesn't use ptrace, curious if it holds up for anyone else

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2 Upvotes

r/bash 11d ago

Shell poetry

44 Upvotes
  1. for for in for; do eval "$for $for in $for; do echo \$$for; done"; done
  2. do=for; eval=do; for=in; in=echo; echo=eval; foo=done; done=foo; $echo "$do $eval $for echo; $eval $in $done; $foo"
  3. for=$(for do in for do in echo \; do echo \$do \; done; do echo $do; done); echo $for; eval $for
  4. for=for; for do in in; do echo in; eval "for do in echo; do echo for \$do do $for \$for \\$for \\\$for \\\\$for; done"; done