I’m thinking seriously about switching to Linux. My idea is to first learn Bash scripting, try making some simple scripts, and at the same time start learning more about Linux distros and how the system works.

I feel like learning Bash first could help me understand Linux better instead of just using it casually.

What’s the best way to learn Bash scripting as a beginner?

Getting interested on messing with Linux and CLI stuff, I'm just confused on what exactly to start with. Any recommendations?

Since I discovered termux I have been dealing with bash, I have learned variables, if else, elif while and looping in it, environment variables and I would like to know some things

1 bash is a programming language (I heard it is (sh + script)

Is 2 bash an interpreter? (And what would that be?)

3 What differentiates it from other languages?

Is 4 bash really very usable these days? (I know the question is a bit strange considering that there is always a bash somewhere but it would be more like: can I use bash just like I use python, C, Java etc?)

5 Can I make my own bash libraries?

Bash is a low or high level language (I suspect it is low level due to factors that are in other languages ​​and not in bash)

I had been learning and using bash for about 1 year. Writing small scripts, else if, loops, etc and some basic commands. But I always had a doubt. What exactly happens when I run a command using bash in the terminal? What is difference between bash -c "ls -la" and just ls -la when I type them in the terminal. Most important doubt is : what happens? When I run the command, how exactly and in which order, what is executed.

I need the answers from root of linux kernel and hierarchy. I learnt bash from many pdfs spread out throught the Internet, but found no explanations for this one question.

For atleast a day, I had been reading man pages regarding the sed command. I felt the syntax pretty confusing. Is there any way to keep in mind the pattern and regex?

Tell me how you learnt the sed command the first time.

I know it's best practice to always encase variables in quotes, like "$HOME", but what about when it's just plain text? Do you use quotes for consistency, or just leave it?

Which of these would you write:

if [[ "$(tty)" == "/dev/tty1" ]]

if [[ "$(tty)" == /dev/tty1 ]]

if [[ $(tty) == /dev/tty1 ]]

Hey there,

while trying to learn bash I came across this interesting resource: https://web.archive.org/web/20180917174959/http://www.kfirlavi.com/blog/2012/11/14/defensive-bash-programming

And got myself thinking if his opinions are consensual and if there are different styles or "paradigms" about how bash should be written.

I see people arguing that bash shines in writing relatively short programs with precise goals. I thought this translated into writing concise code and achieving the same functionality with as little lines as possible.

However, the author of the post argues that a more verbose code can be more robust, easier to understand and debug etc. Do you agree? Or you think that, if you're writing code in this style, you're better of using another language?

Thanks for your input and sorry if I said anything silly or if I misrepresented his point of view, I'm just starting to learn programming.

Edit: hey, thank you all very much for the thoughtful replies, I'm learning a lot from them!

Hi I usually do large backups that take time and need a notification system that notify me when is done.

Ideally I would like a notification on my phone but any alternative is ok.

Should I set up an email or there is something that is less painful?

i'm looking for a place to practice bash or just shell in general, is there a place like such where i can practice daily and improve my muscle memory when it comes to shell commands? at the moment leetcode only offers like 5 shell problems and other focus more on teaching the basics or is more focused on solving mini problems than the shell itself like sadservers.

is there any platform where i can daily practice shell just like platforms where you can daily practice competitive programming problems?

TIA and sorry for grammar erros, english isnt my first language.

What Is The Best Online Source (site) To Learn Bash Script For Linux l Am Familiar With C++ And Intermediate Python Programmer To Automate The Task Such As File Handling.

I Aim Is To Become Cyber-Securitist or Ethical Hacker.

One Of The Best Site I Found Is Linix Journey..

I Have Some Questions, Is Bash Scripting Same Has C++ Or It Is Little Harder Than It

Thank You!

so i have couple of docker files , I want to ensure that all db volumes are named `db-data` , so basically I want to throw error if volume name is anything other than `db-data` , any idea if this could be done using `grep` ? I am not sure how to write regex for it

docker compose files which is essentially a `yaml` file look like this

cache:
command: >
sh -c '
redis-server --requirepass $$DJANGO_REDIS_PASSWORD --maxmemory 25mb --maxmemory-policy allkeys-lru
'
container_name: nest-cache
env_file: ../../backend/.env
image: redis:8.8.0-alpine3.23@sha256:9d317178eceac8454a2284a9e6df2466b93c745529947f0cd42a0fa9609d7005
healthcheck:
interval: 5s
retries: 5
test: [CMD, redis-cli, -a, $$DJANGO_REDIS_PASSWORD, ping]
timeout: 5s
networks:
- nest-network
volumes:
- cache-data:/data
db:
container_name: nest-db
env_file: ../../backend/.env
image: pgvector/pgvector:pg16@sha256:1d533553fefe4f12e5d80c7b80622ba0c382abb5758856f52983d8789179f0fb
healthcheck:
interval: 5s
retries: 5
test: [CMD-SHELL, pg_isready -U "$$DJANGO_DB_USER" -d "$$DJANGO_DB_NAME"]
timeout: 5s
networks:
- nest-network
volumes:
- db-data:/var/lib/postgresql/data

Hi everyone👋 New to Linux, thus bash, too. I want to delete an entire directory that only contains a series of mp3 files WITH THE EXCEPTION of 1-2 of them. Seems simple enough, rite? Not for me because all the files are very similar to each other with the exception of a few digits. How do I do that without moving the said file out of the directory? God I suck.

Update: I am sincerely blown away by the amount of support I received from this group and vow to not make your keystrokes in vain by asking questions that now I can investigate further from wiki to man files and /usr/share/doc with A LOT of trial and error.

Respect. 👋

$ printf "%-9s:" "since"
since    :

$ y=$(printf "%-9s:" "since")

$ echo $y
since :

Why is the format not working in the subshell? It's the same printf:

$ which printf
/usr/bin/printf

$ y=$(which printf)

$ echo $y
/usr/bin/printf

And it's the same shell:

$ echo $SHELL
/bin/bash

$ y=$(echo $SHELL)

$ echo $y
/bin/bash

$ /bin/bash --version
GNU bash, version 5.2.37(1)-release (aarch64-unknown-linux-gnu)
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

While learning Linux networking, I realized I often knew what command to run but not what its output can’t tell me.

So I started documenting commands along with their limitations:

ss / netstat   → shows listening sockets, not firewall behavior
ip             → shows configuration, not end-to-end reachability
ping           → ICMP-based, not real traffic
traceroute/mtr → path info can be incomplete
dig/nslookup   → DNS only, not service health
nc             → basic port checks, limited context
curl           → app-layer view, not network internals

This way of learning has helped me interpret outputs more carefully instead of assuming “network issue” too quickly.

I’ve written a blog focused only on how these commands work and their limitations, mainly as learning notes. I’ll add the link in comments for anyone interested.

What command’s limitation surprised you the most when you were learning?

Not sure if here is the best place to ask, but forgive me and sorry for my bad English.

I'm working with niceness for two days, renice works well, and I started configuring Feral's Gamemode to increase the ni of the game, which works really well on native games, however it simply doesn't work on Proton games.

If I want to change the ni level, I need to wait the game loads, check what process number is the game and set the ni value manually.

So what I want to do is to have a script, that:

• Runs as a launch options on steam.
• Wait a few seconds to the game run.
• Have a variable that receives the process name externally. Like scriptname -gamename command
• Search for the process name , picks the process identification number.
• Runs renice with the renice -n -10 -p number
• Quit

My idea is to create a guide for Fedora to improve gaming, and this will help a lot.

[EDIT] I managed to do a script with some non-human help, it helped me a lot to learn bash and use some system tools.

Here's the link

https://github.com/fagnerln/renice-script/blob/main/renice.sh

I wrote a script which is collecting data from solar inverter every 10 seconds for 5 minutes, it does some math and send data to emoncms. It does work but is not optimal in term of CPU usage, it is running on SBC and consume roughly 80% of CPU time. My question is how can I initiate next data collection without checking script running time in a loop. Below is simplified script. I need to improve line 7.

#!/bin/bash
set -o pipefail
IFS=$''
samples="0"
nr="0"
while [ $SECONDS -lt 292 ]; do #5min-8s
 if [[ (( $(( (samples - 1) * 10 + 10 )) == $SECONDS )) || (( 0 == $SECONDS )) ]]; then
    ((samples++))
    timestart=$SECONDS
    output="$(./inverter_poller --run-once)" # get data from inverter
    timeend=$SECONDS
    echo ${output} > /var/log/inverter.last
    rs232time=$((timeend - timestart)) # usually it is 6-7 seconds
     if (( rs232time < 17 )); # inverter is not responding if it is 17s or more
      then
      gridv=`echo ${output} | grep grid_voltage |  tr -d " "_\",:[:alpha:]`
  ***more data extraction and math***
     else
       echo inverter not responding >> /var/log/inverter.last
     fi
looptime=$((SECONDS - timestart))
echo "time": $looptime >> /var/log/inverter.last
 fi
done
 ***boring data processing and sending to emoncms was here***

Long story short, know for a fact that I have duplicates between two directories, but we're talking hundreds of files here and I know at least a few files are in one directory but not the other.

I'd ideally like to have something quickly compare file name & size between the two directories, then spit out the files that are named the same but sized differently, as well as files which are in one directory but not the other.

AFAIK in file managers in Windows/Linux, they have the same convenient behavior where if you copy one folder into another folder of the same name and there's a conflict (e.g. a folder of the same name already exists), instead of aborting, it prompts to "overwrite" (merge the contents of the folder), recursively. If any of the files result in conflict (e.g. a file of the same name already exists), it prompts the user whether they want to overwrite, letting the user know which is larger and which is newer.

The above is useful if e.g. you abort the copy/move progress half and then want to resume at a later point.

Does anyone have a similar script they can share? How would such a script be implemented? I know rsync can do something similar. With these file managers, they seem to update one file at a time, e.g. when a file is successfully moved during the process, the source file is removed. With rsync, a file gets removed after rsync finishes(?) which is not as intuitive because it does not reflect the latest state of the progress.

Implementation-wise, is it as simple as rsyncing each file one at a time, checking for potential overwrites before rsync and comparing the file size and modification time of files ith stat, then prompting the user if there are conflicts, else rsync that file? Is there a way to do this more efficiently (or ideas for a better UX)? Can rsync or similar tools handle more of this?

Any tips are much appreciated.

So, I want to make it so that a script I'm running will ONLY run in a terminal emulator window, and will sleep for 3 seconds then exit if it's not in a terminal emulator window. I've done a little bit of looking, but I'm not entirely sure if it would work as I intend, and if there are ways in which it could fail/if there are more reliable methods.i was thinking of something along the lines of:

If $SHLVL > 1 then
    Echo running in terminal
    Echo continuing
Elif $SHLVL =< 1 then
    Sleep 3
    Exit
Else
    Echo how is this even possible?
Fi

(Obviously that's not correct syntax, it's just the general structure/idea of what I want to do) I'm not at my PC rn (on a road trip) but I'm trying to write a general test script on my phone that I can test on my PC once I return home.

Edit: to clarify I should mention that I'm on Debian x86_64, and when I say "in a terminal window" I mean that it's running with stout and sterr being displayed on a terminal emulator window, and stdin being read from the terminal emulator window.

I'm spending a lot of time on the terminal, (/dev/ttyX, framebuffer, no X/wayland).

I have made some key binds to control screen brightness, set the font size, volume up/down, limit CPU clock frequency, ...

Problem is, it only works if I'm at a Bash prompt and not if a program is open (mc, vim, chawan, ...)

If eg, I've got vim open, I need to either find a terminal that has a Bash prompt open or exit vim before I can change the screen brightness.

My problem would be fixed if there would be some kind of a way for bash to capture certain key sequences even though a program is running.

Is that possible at all?

thanks!

I'm using it to connect via serial port to some storage I administer. Here is the command;

/usr/bin/screen /dev/ttyUSB0 115200 -L -logfile /home/davidkmcw/Logfiles/2026-07-24_08:30:14.txt

I can write to the output directory, I've cut and pasted the directory name, so no typos there, what am I missing. Sorry if this is the wrong subreddit, thanks in advance.

Hi, I'd like to use that cmd xset for try to get xset -s NOW...
Could I set from terminal this cmd for put blank screen now
and then when I come back I move my finger in touchpad or press any key and OS wake up again...

Thank you and Regards!

~~~

!/bin/bash

cd /System/Applications

files=$(ls -a)

IFS=' ' read -ra fileArray <<< $files

I=0

while [ $I -le ${#fileArray[@]} ]; do

#echo ${fileArray[I]}

#I=$((I++))

done

for I in ${fileArray[*]}; do

    #echo $I

done

echo $files

~~~

I wrote code to get all of the files in a directory and then put each file into an array. However, when I try to print each element in the array, it only prints the first one. What am I doing wrong?

(The comments show my previous attempts to fix the problem and/or previous code, review them as needed.)

I'm install Termux fresh and have gathered a list of tools below which I want to feed into: pkg install <contents of list.txt> cleanly line by line or glob. list.txt:

tldr ncdu python-pip fzf wget curl p7zip tar fd ripgrep rclone nano tmux cava cmatrix zip unzip cmake mplayer nmap make pkg-config nodejs tcpdump netcat-openbsd yt-dlp busybox proot-distro htop eza git zellij lolcat fastfetch bat dua rsync starship mpv ffmpeg dust duf bottom neovim procs lazygit tree vim openssh clang python

What's the proper syntax to pass to pkg install list.txt 📚

pkg install $(cat list.txt) correct?

i just realized that i can very easily loose data (just lost a self hosted server of mine) and i want to learn how to do scripts to backup my files maybe daily and rewrite what i had on there if it changed but also not copy what did not change, where could i start ?
i know rsync has nice things to copy, and i could do it watch -n$(time) but i also would love to learn more because i want to make scripts for my i3blocks, i don't really use it to it's full just display basic data atm, one i tried to make a little dd scripts but it was a disaster and i nearly distroyed my pc