Modify an IPTable Rule to Include Destination Port

I need to create a noscript that reads several iptable rules and adds a destination port. Is there a way to do this without manually parsing the iptables output as text via awk? Ideally I'm hoping there's a way to ask iptables for individual pieces of data about a certain rule so I can save those into variables and then delete the rule and recreate it with the destination port added.

https://redd.it/108wpai
@r_bash

automated corrupt archive testing help

Hi all,

I've been using the snippet below to create a text file with all the corrupt rar filenames in it.

find . -type f -iname '*.cbr' -exec unrar t {} \; 2>"cbrerrors.txt" >"cbroutput.txt"

I can't help but feel, that for a bash guru it would take about 10 seconds to put together a mod that just moves the corrupt files to another location. I don't suppose I could get an assist please ?

Cheers

https://redd.it/10930zt
@r_bash

Replacing string from command output with sed

I am trying to replace a string from a command output but it's not doing anything.

When i do
echo "Usage: swaylock [options]" | sed 's/swaylock/swaylock-corrupter/g'
it successfully replace the string with the new string.

But when i try to do
swaylock --help | sed 's/swaylock/swaylock-corrupter/g'

It simply prints the help docs without replacing the string.
What am I doing wrong?

https://redd.it/1093da8
@r_bash

Trouble generating big random hexadecimal numbers

I want to generate a random number from 2 to $witness_limit ( It's value is a 1025 digit long number ). I've tried using $((2 + RANDOM % $witness_limit)) but it's causing an error due the size of the number also as far as I know $RANDOM has a limit of 32767

#!/bin/bash

generaterandom() {

head -c 256 /dev/urandom | xxd -p -u -c 256 | tr -d '[:space:]\\'
}

p="$(generaterandom)"
q="$(generaterandom)"

n=$(echo "obase=16;ibase=16; ${p} * ${q}" | bc | tr -d '[:space:]\\')

witnesslimit=$(echo "obase=16;ibase=16; ${n} - 2" | bc | tr -d ':space:\\')

https://redd.it/10978v3
@r_bash

What happens when you open a terminal and enter ‘ls’
https://www.warp.dev/blog/what-happens-when-you-open-a-terminal-and-enter-ls

https://redd.it/109czo4
@r_bash

Error while pulling json in youtube-dl Script

Hello Everyone,

I have been using this premade noscript from another reddit user to grab content from Discovery plus and download it using youtube-dl. Recently, it stopped gathering the URLS and I lack the knowledge to fix it. It seems to no longer be getting the json information and filtering through it. Does anyone kno how to fix this?

If this is not allowed via community rules, let me know and I will take it down.

​

https://github.com/ohmybahgosh/YT-DLP-SCRIPTS/tree/main/DISCOVERY-PLUS-YTDLP

https://redd.it/109g561
@r_bash

bash alias show command?

My bash alias file got deleted(nvm how) while I was running the alias commands so currently I have the alias running but the bash alias file has been deleted. Is there a way I can see what the alias is running? I create alias files because I have terrible memory of what I need to run/do for my program.

https://redd.it/109czar
@r_bash

Percentage in file name breaks noscript when assigning output of command to variable

Hi everyone.

So I have this noscript, it runs fine and I was satisfied with it, until I ran into a file that had a percentage on the file name, it brakes the noscript, more specifically when doing what I think is called a subshell, what I want to do is assign the output of a command to a variable.

for i in *; do Hash+=$( sha256sum "${i%}" ); Hash+=$( echo "\n"); done; fi;

When it gets to `Hash+=$( echo "\n")` is when it stops working if there is a file name with a %. I have tried multiple ways of replacing it with printf and adding prefixes before "\\n", but it doesn't work either.

Also, really weird, for me, normally `echo "\n"` will print `\n`, but here it does what it's supposed to and adds a line.

https://redd.it/109mt98
@r_bash

Is sleep in a while true loop acceptable ?

Hello I have a system that has some commands that need to be manually issued when certain conditions are met.

I monitor journal logs to determine when these conditions are met. My current code is just a few lines. It’s just a while true loop which checks the logs from the last 5 minutes and if it finds the condition it issues the command. After that sequence it just sleeps for 5m

Everything works fine but I’m just wondering if sleep is considered amateur or “bad code” if it is should is there a better way I should do it?

I searched around and it seems like it’s ok since people say it doesn’t really consume cpu cycles. Is that correct?

https://redd.it/109u9mx
@r_bash

scp'ing a file name with spaces in it is driving me crazy

I'm trying to make a tool to scp a file to a remote directory and rename it, but it's not working. The scp works when I do it manually e.g.

scp file.mp4 user@host:/path/to/directory/"new name.mp4"

but with the noscript it always fails with

No such file or directory

or

ambiguous target

When there are no spaces in the file name it works fine, and when I do it manually it works fine using 1x quotes for the file name on the local machine and 2x quotes for the file name on the remote machine. The noscript is like this:

echo "Which file to transfer?"
read noscript
echo "What to save it as?"
read name
scp $noscript user@host:/path/to/folder/'"$name"'

There are 2x quotation marks in the location on the remote machine (I even tried 3x quotation marks). This got the error

<last word of the renamed file name>.mp4" No such file or directory

How do I use variable and name with spaces together in a bash noscript??

Thanks

https://redd.it/109tcyn
@r_bash

Alias to locate for greater ease

Hello.

This isn't great code, but it saves you from typing three commands when your locatedb is out of sync with the filesystem, so it was an idea.

I update the locatedb once per day, but that doesn't seem to be enough, I should probably have it run every 2 hours. And still then, it wouldn't be updated enough for me to find that file I want to locate I reckon.

Finding files with locate is so much faster than with find when you know the file name, or large parts thereof, otherwise I tack on a | grep <something> to filter down the output.

If you don't use locate, and you use the apt package manager, then you can install it by:

sudo apt update && sudo apt upgrade -y && sudo apt install mlocate

Anyways, I made an alias, that took care of running sudo updatedb if locate didn't find the file, in the first place, and then ran locate afterwards, so now I know for sure that the file isn't there, or I may re-spell my search. With only one command, instead of three.

alias locate='suomynona() { locate $1 || sudo updatedb && locate $1 ; unset -f suomynona ; } ; suomynona '

And, I reckon this is within the scope of this subreddit, since we are talking about aliases, but by all means, feel free to reimplement it as a function. :)

And the weird function name, is named that way, so I don't undeclare somebody else's function.

Enjoy!

https://redd.it/109ymzz
@r_bash

"While loop" isn't l going through all variables

Starting to get my hands a little more dirty in bash.


I have a input file that contains a list of hosts that I would like to check if "/dump" is mounted.


Currently the list of host has 18 hosts. All are passwordless accessible.


So I pretty much want to ssh into a server and check to see if "/dump" is mounted or not.



#!/bin/bash

while read hostList; do
result=$(ssh "$hostList" 'mount | grep "/dump"')
if -z "$result" ; then
echo "$hostList: /dump is not mounted"
else
echo "$hostList: /mnt is mounted"
fi
done < hostList


I guess the problem is when I run this noscript sometimes it just comes back with 1 result, like it's only hitting the first hostname in the "hostList". Other times it comes back with the first 3 servers in the "hostList".


I can't seem to get it to hit all 18 servers in the "hostList".

https://redd.it/10a2ew9
@r_bash

Arithmetic Expressions

Hello,

I was hoping someone could explain to me what I am doing wrong here. I am a newbie at bash.

In hackerrank (website) there is a task to display a given expression rounded to 3 decimal places.

___________________

|Sample 1 input: |

\---------------------------

5+50*3/20 + (19*2)/7

\-------------------------------------------------------------------------------

\#my_code

\#!/bin/bash

read A

read B

read C

read D

read E

read F

x=$(( $A+$B * $C/$D + ($E**2) / $F ))

echo $x

&#x200B;

\------------------------------------------------------------------------------

The arithmetic works up until I add /F, then the red error marks occur.

If I try to run it I get the following error:

Solution.sh: line 10: A+B*C/D + (E**2) / F : division by 0 (error token is "D + (E**2) / F ")

I've taken the /F out and then the code runs. Is there an operator or syntax format I'm overlooking?

any additional help would be greatly appreciated.

https://redd.it/10agu8e
@r_bash

Why can the terminal not do syntax highlighting for bash the way VSCode can (or even my note taking app Obsidian.md)?



https://redd.it/10an288
@r_bash

Why can't I pipe into the select command

Hello,

I want to make an user interactive selection within a pipe with

any_producing_commands|select menu_item in $(cat); do echo -n "${menu_item}"; break; done|any_consuming_commands

in between other commands.

Example

seq 0 4|select menu_item in $(cat); do echo -n "${menu_item}"; break; done|wc -c

But this breaks the pipe and just prints me the selection menu.

Can somebody tell me why and if possible provide me a solution?

I know this does work, but I want to be able to pipe parameters into the menu:

select menu_item in $(seq 0 4); do echo -n "${menu_item}"; break; done|wc -c

https://redd.it/10aq82w
@r_bash

ramfetch, now with the ascii logo having 2 notches.
https://redd.it/10b2jo2
@r_bash

Search file by name in specific repo to check whether it exists

My task is to check whether some file with a specific name in an arbitrary repo exists and tell user path to it or return null. I am not sure whether I am looking for in the right direction. I don't see REST method that will allow me to do such task directly in this page.

https://redd.it/10b6fxo
@r_bash

Writing a as-portable-as-possible noscript for downloading and compiling an Analog Clock written in my programming language (called AEC).

I've tried to write a as-portable-as-possible noscript for downloading the source code and building the Analog Clock in AEC.

For AEC-to-x86:

mkdir ArithmeticExpressionCompiler
cd ArithmeticExpressionCompiler
if [ $(command -v wget > /dev/null 2>&1 ; echo $?) -eq 0 ] # Check if "wget" exists, see those StackOverflow answers for more details:
                                                                                         # https://stackoverflow.com/a/75103891/8902065
                                                                                         # https://stackoverflow.com/a/75103209/8902065
then
  wget https://flatassembler.github.io/Duktape.zip
else
  curl -o Duktape.zip https://flatassembler.github.io/Duktape.zip
fi
unzip Duktape.zip
if [ $(command -v gcc > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  gcc -o aec aec.c duktape.c -lm # The linker that comes with recent versions of Debian Linux insists that "-lm" is put AFTER the source files, or else it outputs some confusing error message.
else
  clang -o aec aec.c duktape.c -lm
fi
./aec analogClock.aec
if [ $(command -v gcc > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  gcc -o analogClock analogClock.s -m32
else
  clang -o analogClock analogClock.s -m32
fi
./analogClock
        

For AEC-to-WebAssembly:

if [ $(command -v git > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  git clone https://github.com/FlatAssembler/AECforWebAssembly.git
  cd AECforWebAssembly
elif [ $(command -v wget > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  mkdir AECforWebAssembly
  cd AECforWebAssembly
  wget https://github.com/FlatAssembler/AECforWebAssembly/archive/refs/heads/master.zip
  unzip master.zip
  cd AECforWebAssembly-master
else
  mkdir AECforWebAssembly
  cd AECforWebAssembly
  curl -o AECforWebAssembly.zip -L https://github.com/FlatAssembler/AECforWebAssembly/archive/refs/heads/master.zip # Without the "-L", "curl" will store HTTP Response headers of redirects to the ZIP file instead of the actual ZIP file.
  unzip AECforWebAssembly.zip
  cd AECforWebAssembly-master
fi
if [ $(command -v g++ > /dev/null 2>&1 ; echo $?) -eq 0 ]
then
  g++ -std=c++11 -o aec AECforWebAssembly.cpp # "-std=c++11" should not be necessary for newer versions of "g++". Let me know if it is, as that probably means I disobeyed some new C++ standard (say, C++23).
else
  clang++ -o aec AECforWebAssembly.cpp
fi
cd analogClock
../aec analogClock.aec
npx -p wabt wat2wasm analogClock.wat
node analogClock

Is there anybody knowledgeable about various operating systems here to know how to make the noscripts better?

https://redd.it/10b64u7
@r_bash

Learning bash. Why isn't this command outputting when the file changes?

I need a noscript that will continuously output the current battery percentage whenever it changes. I looked online and found that I could use the "entr" program to accomplish this. Here's the noscript I wrote.

\#!/bin/bash

capacity_file="/sys/class/power_supply/BAT1/capacity"

echo $capacity_file | entr sh -c "cat $capacity_file"

&#x200B;

I'd expect this noscript to output the current battery percentage when it's ran, and output the updated percentage every time that it changes. When I run the noscript, I'll get the current percentage of the battery outputted, but when the battery discharges some more, the updated value is never printed to stdout. I can tell that the percentage has updated by manually reading the contents of the capacity file.

&#x200B;

As a proof of concept for the noscript, I updated the capacity_file variable to be "./temp". After running the noscript, I can change value of the temp file by running commands like "echo hello > ./temp". When I run these commands, the noscripts shows the updated value every time.

So why is it that this noscript is working in the temp file example, but not with the battery capacity file?

https://redd.it/10btynr
@r_bash

Group files with same name…

I’m scratching my head thinking on how to achieve this and today group files came to my mind, well, if possible.
I have a directory with more than one video file. I need to convert it through ffmpeg and burn in the source timecode in the converted video. For one file I can to this, not for more than one. The thing is that in order to get the timecode I need to run mediainfo that will generate a txt file with the TC for each video file, getting its name, so I will have file01.mov and file01.txt, file02.mov and file02.txt, and so on. The problem is that ffmpeg will only grab one txt file and all the converted videos will end up with the same burnt TC.
Thanks in advance!

https://redd.it/10cdd63
@r_bash

A shell noscript to check the version of NodeJS doesn't work in Git Bash on Windows.

I am trying to make a shell noscript to automatically download, compile and build some program I've made. You can see the full noscript on my blog. My program requires NodeJS 11 or newer, so I am trying to make my noscript output an appropriate error message in case it's not installed. Here is what I've tried:

node_version=$(node -v) # This does not seem to work in Git Bash on Windows.
# "node -v" outputs version in the format "v18.12.1"
node_version=${node_version:1} # Remove 'v' at the beginning
node_version=${node_version%\.*} # Remove trailing ".*".
node_version=${node_version%\.*} # Remove trailing ".*".
node_version=$(($node_version)) # Convert the NodeJS version number from a string to an integer.
if [ $node_version -lt 11 ]
then
  echo "NodeJS version is lower than 11 (it is $node_version), you will probably run into trouble!"
fi

However, when I try to run it in Git Bash on Windows 10, with NodeJS 18 installed and in PATH, here is what I get:

stdout is not a tty
NodeJS version is lower than 11 (it is 0), you will probably run into trouble!

What is going on here?

https://redd.it/10cip05
@r_bash