How to learn shell noscripting?

I have basic / intermediate knowledge of command line and would like to learn how to use shell noscripting. Are there websites or resources that provide problems that I can try and solve? I am also interested in shell noscripts for HPC so I was wondering what area I should focus on here.

https://redd.it/1erft7a
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tmpmail v1.1.5 now supports receiving attachments
https://redd.it/1erzodj
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What does - and -- mean in bash?

I've come across noscripts that use - or -- for arguments and it's never really explained what they do. What's it called and what's the usage?

# example using -
curl -fsSL 'some_url/install.sh' | env ENV="${HOME}/.bashrc" bash -

# example using --
command -- arg1 arg2

https://redd.it/1erzyy6
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Using read -p to prompt bold variable with ANSI escape codes?

Hi,\
As the noscript, I was wondering if it is possible to do it.\
I've tried 1

var=candy
bold=$(tput bold)
normal=$(tput sgr0)

read -p "IS ${bold}$var${normal} correct? " ans
# assuming answer yes
printf "Your answer is \033[1m%s\033[0m." "$ans"

The output is what I desired, candy and yes are bold.\
I've tried 2

var=candy

read -rep $'Is \033[1m$var\033[0m correct?' ans
printf "Your answer is \033[1m%s\033[0m." "$ans"

It output $var, not candy,\
\
I'd like something similar to second options, that way I can easily make a new line using '\n'. 3\
Is there any better solution? Or better using printf and read separately. Something like

printf "Is \033[1m%s\033[0m correct?" "$var"
read ans
printf "Your answer is \033[1m%s\033[0m." "$ans"

~~I mean read -p is not supported in every shell, maybe it's a good habit to not use -p.~~

https://redd.it/1es3gp5
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Configuration in bash?

I have this piece of code in Python:

URLVARIANTS = {
'barstool': {
'baseurl': 'mcepl@shell.eng.rdu.redhat.com:publichtml/',
'targeturl': 'http://file.rdu.redhat.com/~mcepl/',
'shortenapi': 'https://url.corp.redhat.com/new?'
},
'wotan': {
'baseurl': 'wotan:Export/',
'targeturl': 'https://w3.suse.de/~mcepl/'
},
'tmp': {
'baseurl': 'fedorapeople.org:publichtml/tmp/',
'targeturl': 'https://mcepl.fedorapeople.org/tmp/',
# 'shortenapi': 'http://is.gd/create.php?format=simple&url='
'shortenapi': 'https://da.gd/s?url='
}
}

curconf = URLVARIANTSsite

# now I am using curconf['baseurl'] etc.

How to rewrite it in bash? Yes, I know about https://linuxsimply.com/bash-noscripting-tutorial/array/array-of-arrays/ but the whole is so incredibly finicky and crazy, that I haven’t managed to pull it off (could somebody rewrite this example in the pure sh/bash?). The only alternative I could come up with is to make URL_VARIANTS a string contain JSON object, and then to use jq to separate requested values, but that sounds as a potential PITA as well.

Any thoughts?

https://redd.it/1esg0b3
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[error] guys i think i broke bash in a way never before seen
https://redd.it/1etq4eu
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how do i alias cowsay?

hello, i would like to take the command "cowsay" and alias so every time i type in "endvideo" into the terminal the cowsay command pops up and spits out

"like comment share and subscribe!"

how would i do this?

thank you

https://redd.it/1etti1j
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Limit developers from running a command in command line in a project

We have a fresh Cloudflare worker Typenoscript project in which we currently use wrangler deploy --production command to deploy to production worker.

We want to disable using that command locally and enable it only on the CI/CD pipeline (Github Actions). The problem is that Cloudflare doesn't offer any kind of permissions to do that, except fully limitting developers from accessing Cloudflare by deleting their accounts, and obviously we don't want to do that.

Is there a way of using a bash noscript to accomplish this? And have that noscript fully executable for any developer who would have it locally in the project (git commited to the repository)?

I am fairly new to bash, so I'm not even sure I asked the right question, but I'd say you get the jist.

Also we are open to any other ideas to accomplish this.

Thanks

https://redd.it/1etywgb
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Any tricks to not have to escape a quote?

I have a pretty lengthy cURL that looks something like this:

--data '{
"denoscription": "Foo",
"expression": "this is csdude\'s, it has \"this\", \"that\", and \"the other thing\""
}'

The real one is much longer; the longest is about 3800 characters, and there are 5 of them called in the bash noscript.

For the sake of easier coding and minimizing typos, is there a way to NOT have to escape all of the inner quotes?

I tried surrounding it with `, but that just threw an error :-/

https://redd.it/1eu9je9
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More fun with jq, getting results into a usable array

I'm using this in a cURL to get the data from `result[]`:

foo=$(curl --request GET \
--silent \
--url https://example.com \
--header 'Content-Type: application/json' | jq -r '.result[]')



When I print $foo, this is what I have:

[key]
default

firewall_custom
zone
34
[
{
"id": "example",
"version": "6",
"action": "block",
"expression": "lorem",
"denoscription": "ipsum",
"last_updated": "2024-08-15T19:10:24.913784Z",
"ref": "example",
"enabled": true
},
{
"id": "example2",
"version": "7",
"action": "block",
"expression": "this",
"denoscription": "that",
"last_updated": "2024-08-15T19:10:24.913784Z",
"ref": "example2",
"enabled": true
}
]



What I need from this is to create a loop where, in a series of addtional cURLs, I can insert action, expression, and denoscription.

I'm imagining that I would push these to 3 separate arrays (action, expression, and denoscription), so that ${action\[0\]} would coincide with ${expression\[0\]} and ${denoscription\[0\]}, and so on.

Something along the lines of:

# assuming that I have somehow created the following arrays:
# action=("block" "block")
# expression=("lorem" "this")
# denoscription=("ipsum" "that")

for x in ${action[@]}; do
bar=$(curl --request GET \
--silent \
--url https://example.com \
--data '{
"action": ${action[$x]},
"expression": ${expression[$x]},
"denoscription": ${denoscription[$x]}
}' | jq '.success')

if [[ $bar == true ]]
then
printf "$x succeeded\n"

else
printf "$x failed\n"
fi

# reset bar
bar=''
done


The question is, how to create action, expression, and denoscription arrays from the results of $foo (that original cURL)?

https://redd.it/1euba4a
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Tab-completion for a command name

I have two custom commands: play-music and play-video. I want to write a bash noscript that allows me to autocomplete these commands when I press TAB.

For example:

$ play<TAB>
play-music play-video

$ play-vi<TAB>
play-video

I’ve found a tutorial on creating a bash-completion noscript, but it only works for command arguments. How can I achieve this for the command names themselves?

https://redd.it/1eugy51
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what is an "option" in bash? and how is it different the other arguments?

so i understand what an argument is, i understand that an option is a type of argument,

but what i don't understand is how an option is different then other types of arguments

can someone explain it to me?

thank you

https://redd.it/1eujcim
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GitHub - AnonAmosAdmn/OTTO-STACK-DEPLOYER
https://github.com/AnonAmosAdmn/OTTO-STACK-DEPLOYER

https://redd.it/1euwj08
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Bashtutor - interactive bash tutorial


I wrote a minimal framework for creating CLI obstacle courses.
Currently there is one "module" which is for Bash itself.
While its a proof of concept, I attempted to make it entertaining and smoothen the edges as much as I could.
The main inspiration was vimtutor and how I would have liked something like this back when I was starting out.

https://github.com/agvxov/bashtutor

I'm hoping it will be useful to someone somewhere.

https://redd.it/1ev6ex5
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I have written some helper noscripts to simplify on-demand GNU/Linux proxy configuration
https://gitlab.com/brlin/linux-proxy-configuration-helper

https://redd.it/1ev7j98
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Interpolation and sed!

I hope this helps somebody, like it did for myself, last week.

I love this shit. And I am always happy to share/ read contructive critiscism.

I got tasked with a set of instructions, under immense pressure, the other day.

I needed to edit a 20k line file, and was told it needed batching into many, 100 line files, to avoid deadlocking our DB whilst running the finished article. In total, we were deleting millions of duplicate rows, with specific IDs. I also needed to add a comma, at the end of each newline (so far, no sweat). So I did for i in x*; do cat "$i" | tr \\n , >> $i.new;

I then batched that file, into many smaller ones, running split -l 100 FILE.txt. The newly created batched files then had naming conventions like, `xaa.new`, `xab.new` etc.

But, after I had done this, I discovered that I also needed to remove the very last comma in each file. This is so that the syntax is accepted by MySQL. So I did - for i in x*; do sed -e '$s/,$//' "$i" > "$i".new.

Then, here's the interpolation... courtesy of my wise and all-knowing colleague, who just happened to shoot me a message, making sure I was ok. I was stuck on how to run the MySQL statement, using the content in all my files. I was also very nervous, at this point. We ended up writing, for i in x*; do mysql databaseName -vvv -e "DELETE from table where table_id in ($(cat $i))" >> /home/userName/incidentNumber/output.sql after we had tested SELECT statements, echo'ing output (without any MySQL) and had it approved by all stakeholders.

I felt very accomplished, as I always do when I learn something new, and needed a little nudge to get over the line, in the end. But my goodness, it was such a rush! I hope someone finds this useful and/ or interesting. I know I did.

https://redd.it/1evju1s
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mirror one GNU Screen session to another?

I'd like to create two screen sessions, then mirror the activity of one to another. So, if I create session_1 in one Terminal window, and create session_2 in another Terminal window, they'd look the exact same if I ran a certain program in session_1. It'd also be nice if detaching session_1 detached session_2 as well.

Is this possible using functionality built into screen, or would if be more complicated? I can't find anything about this online, so I'm guessing it's the latter.

https://redd.it/1evp3t5
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Trap not taking effect in POSIX noscript

In this noscript I launch vim opening a temp file in the terminal window. If the terminal window is closed with vim running, the temp file should be deleted. Closing the terminal window should also kill vim process.

However, closing the terminal window doesn't remove the file and the vim process lingers when the terminal window is closed. If I remove the trap command, then the vim process will terminate as expected but the temp file will of course remain.

Any ideas? I have exec sh -c because for some reason without it, vim process lingers when its terminal window closes.

https://redd.it/1evoe9l
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Expanding filenames containing spaces with readlink in a bash noscript

Several programs don't remember the last document(s) they worked with given by command line, e.g. eog ("Eye of GNOME Image Viewer"). So i wrote a general noscript:

- when given command line args: expand them with readlink, call eog, and store expanded names in <last-args-file>.
- when given no command line args at current invocation: load the files specified on command line at last time of invocation, stored in <last-args-file>

This mechanism works quite fine, so far i don't need that it does not allow specifying other parameters to the "wrapped" programs.

The question: see commented code ("DOES NOT WORK") in lastargs.sh. My intent is to clean up files that do not exist anymore since the last invocation. But $(expandargs "$ARGS") returns empty paths when paths contains spaces.

Any idea/hint? Thank you.

btw. eval was used to allow invocations like PRG="QTSCALEFACTOR=1.8 /opt/libreoffice/program/oosplash"

eog:

#!/bin/bash

FILENAME="eog-lastargs.txt"
PRG=/usr/bin/eog

source ~/bin/lastargs.sh

lastargs.sh:

# Specify the folder to check
FOLDER="$HOME/.config/last-args"

if [[ "$1" == "c" || "$1" == "clear" ]]; then
rm -f "$FOLDER/$FILENAME"
exit 0
fi

expandargs() {
expandedargs=""

for arg in "$@"; do
# Resolve the full path using readlink and add it to the
# expandedargs string
fullpath=$(readlink -e "$arg")
if [[ $? == 0 ]]; then
expandedargs+="\"$fullpath\" "
fi
done

# Trim the trailing space and return the full string
echo "${expandedargs% }"
}

# Check if there are no command line arguments
if $# -eq 0 ; then
# Specify the file to store the last command line arguments
FILE="$FOLDER/$FILENAME"

# Check if the specified folder exists
if ! -d "$FOLDER" ; then
# If not, create the folder
mkdir -p "$FOLDER"
fi

# Check if the file with the last command line arguments exists
if -f "$FILE" ; then
# Read the last command line arguments from the file
ARGS=$(cat "$FILE")

# DOES NOT WORK
# - returns empty paths when path contains spaces
#ARGS=$(expandargs "$ARGS")
#echo "$ARGS" > "$FOLDER/$FILENAME"

# Start with the content of the file as command line arguments
eval "$PRG $ARGS" &
else
# Start without command line arguments
eval "$PRG" &
fi
else
ARGS=$(expandargs "$@")
# Write the current command line arguments to the file in the
# specified folder
echo $ARGS > "$FOLDER/$FILENAME"
# Start with the provided command line arguments
eval "$PRG $ARGS" &
fi

https://redd.it/1evv3q2
@r_bash

Could you help me debug this ChatGPT-created noscript that deleted my pdfs?

I asked ChatGPT to create a noscript that changes names of magazines to be consistent with each other (All in the same format), and it deleted all of my files. (Thankfully, I had a backup). Is ChatGPT's fix good? (I asked it to make it not change their directory anymore, not realizing it just outright deleted them). Here is the noscript:

Sorry, I can't seem to format it

# #!/bin/bash

# Function to rename PDF files

rename_pdfs() {

local dir="$1"

local parent_dir="$(basename "$(dirname "$dir")")"

local grandparent_dir="$(basename "$(dirname "$(dirname "$dir")")")"

# List PDF files in alphabetical order

pdf_files=("$dir"/*.pdf)

IFS=$'\\n' sorted_files=($(sort <<<"${pdf_files[*\]}"))

unset IFS

# Rename files with the desired format, ensuring they stay in the same directory

count=1

for file in "${sorted_files[@\]}"; do

if [[ -f "$file" \]\]; then

base_number=$(printf "%02d" "$count")

new_name="${grandparent_dir}_${parent_dir}_${base_number}.pdf"

mv "$file" "$dir/$new_name" # This keeps the file in the same directory

((count++))

fi

done

}

# Export function so it's available in subshells

export -f rename_pdfs

# Find all directories 2 levels deep and rename PDFs

find . -type d -mindepth 2 -maxdepth 2 -exec bash -c 'rename_pdfs "$0"' {} \\;

https://redd.it/1ewcs17
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Had a suit made they asked if I wanted anything embroidered...
https://i.imgur.com/pIx5eXT.jpg

https://redd.it/1ewit33
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