Globbing expansion within variable

I notice this simple noscript behaves differently in bash and zsh

#! /bin/zsh
while read lin
do
echo DEBUG line $lin
done << EOJ
foo * bar
EOJ

In zsh I get the expected output `DEBUG line foo * bar`, but with bash the asterisk is expanded to a list of the files in the current directory. It happens with standard input as well as with HERE documents.

What bash setting could be causing this double evaluation/expansion after assignment, and how do I get similar behavoir to zsh? I do not have any glob or expansion parameter settings in my `.bashrc` so it seems to be a difference with the default bash settings in Ubuntu.

I do not want input text to be interpreted or expanded in any way unless I explicitly use `eval` or `$()`as this is a security risk.

https://redd.it/1hg8crb
@r_bash

Reflow-safe right-aligned text in terminal via bash?

For styling my PS1, I create a a separator line using ANSI escape codes to create a string of $COLUMNS spaces which is underlined in gray. A simplified form of this would be

PROMPT_COMMAND='PS1=$(printf "\[\033[4;37m%${COLUMNS}s\033[0m\]" " ")"\n\s-\v$ "'

https://preview.redd.it/gdv4df0m3d7e1.png?width=901&format=png&auto=webp&s=1a0d6b7860356d7b2b31dba3a384f3b15fc0c42d

However, this messes up the display when the screen contents get reflowed, e.g. switching from a maximized to a half-screen window. Then I get something awkward like this:

https://preview.redd.it/5dj8l8zh4d7e1.png?width=565&format=png&auto=webp&s=87b998dff60c1bb61c172d2884a3a54f577478b2

https://preview.redd.it/ev36rx2n4d7e1.png?width=901&format=png&auto=webp&s=715dac21d32ac06ef29c5fdd600dd46c09764712

Is it possible to instead genuinely *right-align* a text on the terminal, such that it remains at the right end even if *$COLUMNS* changes? Or, alternatively, is there a way to insert a horizontal line that self-resizes like *<hr>* in HTML?

https://redd.it/1hg5ouj
@r_bash

Matches - A CLI game I coded in Bash

It's based on a two player game that was played in the trenches of World War One.

I made the game as an exercise in learning three new skills with Bash.

YouTube video showing the game being played: https://www.youtube.com/watch?v=24Wrz82JowA

Git Repo to download the game: https://git.zaks.web.za/thisiszeev/matches

Download it, try it out, give me feedback, something something something, profit.

https://redd.it/1hgq6r3
@r_bash

Two different while loops

Is there a functional difference between these two while loops:

find /path/ -type f -name "file.pdf" | while read -r file; do
echo $file
done


while read -r file; do
echo $file
done < <(find /path/ -type f -name "file.pdf")

https://redd.it/1hh3kpt
@r_bash

simple bash noscript/syntax help?

Hi there -

I'm looking for help with a fairly simple bash noscript/syntax. (If this isn't the right place, let me know!)

I am trying to write a noscript that will be run frequently (maybe every 10 minutes) in a short mode, but will run a different way (long mode) every 24 hours. (I can create a specific lock file in place so that it will exit if already running).

My thinking is that I can just...

* check for a timestamp file
* If doesn't exist, run **echo $(date) > tmpfile** and run the long mode(assuming this format is adequate)
* if it exists, then pull the date from tmpfile into a variable and if it's < t hours in the past, then run the short mode, otherwise, run it the long mode (and re-seed the tmpfile).

Concept is straightforward, but I just don't know the bash syntax for pulling a date (string) from a file, and doing a datediff in seconds from now, and branching accordingly.

Does anyone have any similar code snippets that could help?

https://redd.it/1hh2wfx
@r_bash

any way I can improve this bash noscript that has double stow command?

stow doesn't delete. It can only throw error or use --adopt to overwrite MY REPO's files instead of overwriting computer files with dotfiles.
I know normal ln can overwrite destination files like this:

ln -sf ~/.dotfiles/alacritty ~/.config/alacritty

but I want to use stow. Current config works decently well but I was wondering if I can replace 2 stow lines with 1?

# this code clones repo, runs install noscript, cd's into that repo, uses stow to distribute files via stow.

# I need to repeat stow twice. First so that if files exist already, those files overwrite
# this git repo files, then I reset this repo and run stow again.
# all this because git stow can't overwrite files / directories if they are already present

git clone --recurse-submodules git@github.com:monoira/.dotfiles.git ~/.dotfiles &&
  bash ~/.dotfiles/install_noscripts/_install.sh &&
  cd ~/.dotfiles &&
  stow -v --adopt alacritty cmus git nvim sqlfluff tmux zsh &&
  git add . && git reset --hard &&
  stow -v --adopt alacritty cmus git nvim sqlfluff tmux zsh

https://redd.it/1hh740o
@r_bash

Find files larger than X mb and promp to delete/skip each one found

Hi. I've asked Gemini, Copilot, Claude, etc. for a bash noscript to find files larger than X mb (this should be a parameter to the noscript) starting in the current path, recursively, and then read (prompt) a question to delete or skip each one found.

I've got this:

#!/bin/bash

if [ $# -ne 1 ]; then

echo "Usage: $0 <size_in_MB>"

exit 1

fi

size_in_mb=$1

find . -type f -size +"${size_in_mb}M" | while IFS= read -r file; do

# Get the file size

size=$(du -h "$file" | cut -f1)

echo "File: $file"

echo "Size: $size"

while true; do

read -p "Do you want to delete this file? (y/n): " choice

case "$choice" in

[Yy]* )

rm "$file"

echo "Deleted: $file"

break

;;

[Nn]* )

echo "Skipped: $file"

break

;;

* )

echo "Please answer y or n."

;;

esac

done

done

When executing "./findlargefiles.sh 50", I'm getting an infinite loop of
"Please answer y or n."

Any ideas? I'm trying it on an Ubuntu 22.04 server

Thanks

https://redd.it/1hhtp6g
@r_bash

Rate my Ubuntu debloater bash noscript

(I give you permission to steal it)

https://redd.it/1hhw6xe
@r_bash

tuiplette, a terminal match-three game (Bash)
https://www.reddit.com/gallery/1hhsh04

https://redd.it/1hi3fz8
@r_bash

Need help understanding and altering a noscript

Hello folks,

I am looking for some help on what this part of a noscript is doing but also alter it to spit out a different output.

p=system_profiler SPHardwareDataType | awk '/Serial/ {print $4}' | tr '[A-Z]' '[K-ZA-J]' | tr 0-9 4-90-3 | base64


This is a part of an Intune macOS noscript that creates a temp admin account and makes a password using the serial number of the device. The problem I am having is that newer macbooks don't contain numbers in their serial! This is conflicting with our password policy that requires a password have atleast 2 numbers and 1 non-alphanumeric.

I understand everything up to the tr and base64. From what I've gathered online, the tr is translating the range of characters, uppercase A to Z and numbers 0 to 9 but I can't get my head around what they're translating to (K-ZA-J and 4-90-3). After this I'm assuming base64 converts the whole thing again to something else.

Any help and suggestions on how to create some numerics out of a character serial would be greatly appreciated.

https://redd.it/1hiiopc
@r_bash

Executing a noscript from another noscript programmatically (regardless of run location)

I'm trying to build a simple noscript that will stop my docker containers, drop a volume, then start my containers back up. To start my containers, I have a helper noscript in the root of my project, compose.sh. The noscript I'm creating is in a subfolder, noscripts.

Is there a way to essentially do "if subfolder, go up a folder, then run noscript"? If I run the noscript from the root, it'd need to search the current location for the compose noscript. If run from elsewhere, it'd need to go up a level from the noscript's location to find the compose noscript.

I know I can hard code the noscript, but that's inflexible, as if the noscript is moved to another machine, it'd need to be modified. I don't know if my thinking of how to write this noscript is wrong, and would appreciate any feedback.

https://redd.it/1hhbaz2
@r_bash

Change terminal color programmatically?

Hello mates, I am using bash terminal. I can change my terminal color if an ssh session is opened. I wrote a function if "$SSH_CONNECTION" then the terminal color is changed. However, I want to do similar change for virtualenv, nothing happens. I print "$VIRTUAL_ENV" and it's null. What should I do?

https://redd.it/1hj8oof
@r_bash

Why variable is not updated in the function called in a while loop?

```
readonly BATTERY_CRITICAL_THRESHOLD=15
readonly REFRESH_INTERVAL=1

readonly BAT_PATH="/sys/class/power_supply/BAT0/capacity"

BATTERY_ALERT_STATE=0

get_battery_status() {
local battery_pct ac_state icon
battery_pct=$(<"$BAT_PATH")
ac_state=$(<"$AC_PATH")

if ((battery_pct <= BATTERY_CRITICAL_THRESHOLD)) && ((BATTERY_ALERT_STATE == 0)); then
BATTERY_ALERT_STATE=1
notify-send "Battery Critical" "Battery level is at $battery_pct%"
elif ((battery_pct > BATTERY_CRITICAL_THRESHOLD)) && ((BATTERY_ALERT_STATE == 1)); then
BATTERY_ALERT_STATE=0
fi
printf '%s%%' "$battery_pct"
}

# Main loop in main shell context
while true; do
get_battery_status
sleep "$REFRESH_INTERVAL"
done
```

Above is a bash noscript I write.

What I expect is it will change `BATTERY_ALERT_STATE` to 1 when battery level is lower than 15, and then send a notification. After `BATTERY_ALERT_STATE` is changed to 1, it won't be changed until the battery_pct is greater than `BATTERY_CRITICAL_THRESHOLD`.

But, in practice, it's not the case, it seems that `BATTERY_ALERT_STATE` has never been changed, and therefore the notification is continueously being sent.

I don't know why, I have debugged it for days, searched online and asked ai, no result.

Can anyone told me why?

https://redd.it/1hjbl7t
@r_bash

XDG & ~/.bashrc

I created a file to be sourced by bashrc to organize directories and files after running xdg-ninja.
I'm just not sure it's fool proof. I was hoping that a more experienced user could comment.
This is a shortened version with only one example. (cargo)

\#! /usr/bin/env dash



\# shellcheck shell=dash

\# shellcheck enable=all



\#------------------------------------------------------------------------------|

\# xdg-ninja

\#------------------------------------------------------------------------------|

alias 'xdg-ninja'='xdg-ninja --skip-ok --skip-unsupported' ;



\#------------------------------------------------------------------------------|

\# XDG Base Directory specification:

\#------------------------------------------------------------------------------|

export XDG_CACHE_HOME="${HOME}/.cache" ;

export XDG_CONFIG_HOME="${HOME}/.config" ;

export XDG_DATA_HOME="${HOME}/.local/share" ;

export XDG_STATE_HOME="${HOME}/.local/state" ;



\#------------------------------------------------------------------------------|

\# xdgmv

\#------------------------------------------------------------------------------|

xdgmv () {

test "${#}" -ne '2' && return ; test -e "${1}" || return ;

if test -d "${2%/*}" ;

then

mv --backup='numbered' --force "${1}" "${2}" ;

else

mkdir -p "${2%/*}" &&

mv --backup='numbered' --force "${1}" "${2}" ;

fi ;

} ;



\#------------------------------------------------------------------------------|

\# [cargo\]: "${HOME}/.cargo"

\#------------------------------------------------------------------------------|

xdgmv "${HOME}/.cargo" "${XDG_DATA_HOME}/cargo" &&

export CARGO_HOME="${XDG_DATA_HOME}/cargo" ;



\#------------------------------------------------------------------------------|

\# unset function(s)

\#------------------------------------------------------------------------------|

unset xdgmv ;



\#------------------------------------------------------------------------------|



https://redd.it/1hjybbv
@r_bash

friends I am looking for this but if you know bash manager types similar to this, can you share it?

https://redd.it/1hk3jpb
@r_bash

Grep question about dashes

Im pulling my hair out with this and could use some help. Im trying to match some strings with grep that contain a hyphen, but there are similar strings that dont contain a hyphen. Here is an example.

echo "test-case another-value foo" | grep -Eom 1 "test-case"
test-case
echo "test-case another-value foo" | grep -Eom 1 "test"
test
I dont want grep to return test, I only want it to return test-case. I also need to be able to grep for foo if needed.

https://redd.it/1hk9edb
@r_bash

Array lengths - this works but the traditional method doesn't

Any ideas? The first one works, The second one doesn't in a noscript, doing a test from the command prompt all is good. Its a simple list of numbers all <100 , array length < 10

len="$(echo "${nlist[@]}" | wc -w)" # Good
len="${#nlist@}" # Bad

https://redd.it/1hkn7gw
@r_bash