Automation Shell Script for CTFs

Here is the code: https://codefile.io/f/l9LmkIdHZK

I am new to shell noscripting; I just know few Linux Commands. I was hoping if someone could check the code I have written and help me improve my shell noscript skills. I am trying to build an automation noscript for CTF's. I want to save my time by not executing all same commands again and again for every target.

I know there's a lot of if statement. I want to know how to make this more effective and faster.

https://redd.it/1ft3dsf
@r_bash

TBD - A simple debugger for Bash

I played with the DEBUG trap and made a prototype of a debugger a long time ago; recently, I finally got the time to make it actually usable / useful (I hope). So here it is~ https://github.com/kjkuan/tbd

I know there's set -x, which is sufficient 99% of the time, and there's also the bash debugger (bashdb), which even has a VSCode extension for it, but if you just need something quick and simple in the terminal, this might be a good alternative.

It could also serve as a learning tool to see how Bash execute the commands in your noscript.

https://redd.it/1ft5r7h
@r_bash

Output a section of stdout

Imagine the output from wpctl status:

...
- Some info
- Some info

Audio:
- Some info
- ...
- Some info

Video:
- Some info
...

I want to get the block of output under "Audio", so the output between "Audio" and "Video". Is there a efficient way to achieve this, e.g. with sed or awk... or grep... ?

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

¿Cómo puedo realizar un noscript en Ubuntu que envíe correos electrónicos con el uso del disco desde la terminal?



Es una tarea nose si me pueden ayudar, ya investigue y no me sale nada alguien que me ayude porfa 🫠

https://redd.it/1ftz0pg
@r_bash

How can I make a noscript in Ubuntu that sends emails with disk usage from the terminal?

It's a task I don't know if you can help me, I've already investigated and nothing comes up, someone help me please 🫠

https://redd.it/1fuis7w
@r_bash

Help creating noscript to email on boot

I am looking for help in creating a noscript to email me when a system boots or reboots. I have tried various online sources but nothing seems to work. I would like to have my Raspberry Pi running Raspbian email me when it boots. I have frequent power outages and want to be able to have the always on Pi let me know when it boots so that I know the power had gone out and I can check the logs for the duration.

Can anyone help me with this?

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

weird behavior from a bash line

hi there,

I wonder why :


find /home/jess/* -type f -iname "*" | wofi --show=dmenu | xargs -0 -I vim "{}"


returns


xargs: {}: No such file or directory

why the find arg isn't passed to vim ?
thx for help guys and girls

https://redd.it/1fuq7r2
@r_bash

what does the $ BY ITSELF mean in bash?

i understand it has something to do with variables but i googled it and it couldn't get a straight answer on what the $ alone means, so i wanted to ask here

thank you

https://redd.it/1fv4k1r
@r_bash

ffmpeg bash question - How to create bash to cut out intro and outro from multiple videos

I'm trying to cut the intro and outro out of multiple videos with different beginning times and different end times using ffmpeg

The code I know of that will do this from a single video is

"ffmpeg -ss 00:01:00 -to 00:02:00 -i input.mkv -c copy output.mkv"

But I don’t know how to tell ffmpeg to do this for multiple videos and to do this with different beginning times and different ending times so that it will do one right after the other

I am new to all of this so if anyone could help me, that would be amazing, thank you

https://redd.it/1fwjvy8
@r_bash

How do i change the colors of that bar?

https://preview.redd.it/w3hvszskswsd1.png?width=1032&format=png&auto=webp&s=5b31a400d02ea56e41adeb17da96327373068443

Hello, so i am using Chris Titus Tech's custom bash config but the colors dont fit with the pallete of my terminal (im making my system Dune themed).

Here is the .bashrc file: https://github.com/ChrisTitusTech/mybash/blob/main/.bashrc , i really tried to find where i can change those colors but couldnt find the line.
My ocd is killing me ;(

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

what does "echo $$" do?

so question, what does "echo $$" do?

some people are saying that it prints the PID of the current instance of the shell you are on

other people are saying that it prints the PID of "a" or "the" noscript that's currently executing?

which is it? or is it both?

thank you

https://redd.it/1fwp9lf
@r_bash

How do I replace part of a line with the output of a variable?

Hi all,

I am writing a noscript that will update my IPv4 on my Wireguard server as my dynamic IP changes. Here is what I have so far:

#! /bin/bash

CurrentIP= curl -S -s -o /dev/null http://ipinfo.io/ip

WireguardIP= grep -q "pivpnHOST=" /etc/pivpn/wireguard/setupVars.conf |tr -d 'pivpnHOST='

if "$Current_IP" = "$Wireguard_IP" ;then
exit
else
#replace WireguardIP with CurrentIP in setupVars.conf
fi
exit 0


when trying to find my answer I searched through stack overflow and think I need to use awk -v, however; I don't know how to in this case. Any pointers would be appreciated.

https://redd.it/1fwxq9l
@r_bash

Rate my bash noscript
https://drive.google.com/file/d/1q7DVciDMbCrO4YyV6U4S4StgZ2ll5MFu/view

https://redd.it/1fx3pbb
@r_bash

Getting the “logname” of a PID

Say I log into a box with account “abc”. I su to account “def” and run a noscript, helloworld.sh, as account “def”. If I run a ps -ef | grep helloworld, I will see the noscript running with account “def” as the owner. Is there a way I can map that back to the OG account “abc” to store that value into a variable?

Context: I have a noscript where I allow accounts to impersonate others. The impersonation is logged in the noscript’s log via the logname command, but I also have a “current users” report where I can see who’s currently running the noscript. I’d like the current users report to show that, while John is running the noscript, it’s actually Joe who’s impersonating John via an su.

I’ve tried ps -U and ps -u, but obviously, that didn’t work.

https://redd.it/1fx6n52
@r_bash

Shell noscripting projects for 1 yoe helpdesk to get promoted to a new role?

What could that be?(in new company-switch)

https://redd.it/1fx6m6a
@r_bash

How do I finish a pipe early?

Hi.

I have this noscript that is supposed to get me the keyframes between two timestamps (in seconds). I want to use them in order to splice a video without having to reencode it at all. I also want to use ffmpeg for this.

My issue is that I have a big file and I want to finish the processing early under a certain condition. How do I do it from inside of an awk noscript? I've already used this exit in the early finish condition, but I think it only finishes the awk noscript early. I also don't know if it runs, because I don't know whether it's possible to print out some debug info when using awk. Edit: I've added print "blah"; at the beginning of the middle clause and I don't see it being printed, so I'm probably not matching anything or something? print inside of BEGIN does get printed. :/

I think it's also important to mention that this noscript was written with some chatgpt help, because I can't write awk things at all.

Thank you for your time.

https://pastebin.com/cGEK9EHH

#!/bin/bash
set -x #echo on
SOURCEVIDEO="$1"
STARTTIME="$2"
ENDTIME="$3"

# Get total number of frames for progress tracking
TOTALFRAMES=$(ffprobe -v error -selectstreams v:0 -countpackets -showentries stream=nbreadpackets -of csv=p=0 "$SOURCEVIDEO")
if -z "$TOTAL_FRAMES" ; then
echo "Error: Unable to retrieve the total number of frames."
exit 1
fi

# Initialize variables for tracking progress
framesprocessed=0
startframe=""
endframe=""
startdiff=999999
enddiff=999999

# Process frames
ffprobe -showframes -selectstreams v:0 \
-printformat csv "$SOURCEVIDEO" 2>&1 |
grep -n frame,video,0 |
awk 'BEGIN { FS="," } { print $1 " " $5 }' |
sed 's/:frame//g' |
awk -v start="$STARTTIME" -v end="$ENDTIME" '
BEGIN {
FS=" ";
print "start";
startframe="";
endframe="";
startdiff=999999;
enddiff=999999;
betweenframes="";
print "startend";
}
{
print "processing";
current = $2;

if (current > end) {
exit;
}

if (startframe == "" && current >= start) {
startframe = $1;
startdiff = current - start;
} else if (current >= start && (current - start) < startdiff) {
startframe = $1;
startdiff = current - start;
}

if (current <= end && (end - current) < enddiff) {
endframe = $1;
enddiff = end - current;
}

if (current >= start && current <= end) {
betweenframes = betweenframes $1 ",";
}
}
END {
print "\nProcessing completed."
print "Closest keyframe to start time: " startframe;
print "Closest keyframe to end time: " endframe;
print "All keyframes between start and end:";
print substr(betweenframes, 1, length(betweenframes)-1);
}'

Edit: I have debugged it a little more and I had a typo but I think I have a problem with sed.

ffprobe -showframes -selectstreams v:0 \
-printformat csv "$SOURCEVIDEO" 2>&1 |
grep -n frame,video,0 |
awk 'BEGIN { FS="," } { print $1 " " $5 }' |
sed 's/:frame//g'

The above doesn't output anything, but before sed the output is:

38:frame 9009
39:frame 10010
40:frame 11011
41:frame 12012
42:frame 13013
43:frame 14014
44:frame 15015
45:frame 16016
46:frame 17017
47:frame 18018
48:frame 19019
49:frame 20020
50:frame 21021
51:frame 22022
52:frame 23023
53:frame 24024
54:frame 25025
55:frame 26026

I'm not sure if sed is supposed to printout anything or not though. Probably it is supposed to do so?

https://redd.it/1fxhx2n
@r_bash

How are if, case, etc implemented internally?

I was thinking about it and I realized I had no idea- how do if, for, while, case, etc, all control the execution of separate commands on other lines? For example


if [ "$thing" == "blah" ]; then
echo "How does it know to not run this command if thing is not blah??"
fi

Is this something only builtin commands have the power to do? Or could if, case, etc, theoretically be implemented as external programs?

https://redd.it/1fxnch3
@r_bash

this will probably be very complex

im tryting to create a noscript where i can pick up a text with some image links in the middle and input that into a tui like less will all the images loaded with ueberzug.

i know that is possible because there are noscripts like ytfzf that is capable of doing something close.

the tool im using to get the texts with image links in the middle is algia(terminal nostr client).

to be honest a vim tui would make it more usable but i dont know if this would be much more complex so something like less but that is capable o loading tui images would be more than enought.

i use alacritty.

https://redd.it/1fxwrw2
@r_bash

Does export supposed to create a permanent environment variable?

For many guides for installing packages out there, I always see this as a step to installing the package, for example...

```
export JAVA_HOME=/opt/android-studio/jbr
```

And it does work. It does create a env variable (In the example above JAVA_HOME) but when I close the terminal and the next time I launch the terminal, the env variable is not there and the packages need these variables setup for all sessions.

Am I doing something wrong? Why do many guides tell you to simply run `export` instead of edit the `/etc/profile` file by adding the `export` command to the end of the `/etc/profile` file which will make the env variable in all terminal sessions?

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

I habe 10 hours to learn bash. What would you do?

Hey, people, I have 10 hours of free time to learn simple bash noscripting. Maybe even more.

I already know how to use commands in cli, I worked as a developer for 5 years and even wrote simple DevOps pipelines (using yml in GitHub)

But I want to go deeper, my brain is a mess when it comes to bash

It's embarrassing after 5 years in coding, I know.

I don't even know the difference between bash and shell. I don't know commands and I am freaked out when I have to use CLI.

I want to fix it. It cripples me as a developer.

Do you know a some ebooks or something that can help me organise my brain and learn all of it?

Maybe fun real-world projects that I can spin out in a weekend?

Thank you in advance!

https://redd.it/1fy4xhy
@r_bash

How can I use a bash/grep search in vim?

Looking at the contents of both /r/bash and /r/vim, it seems the question is best placed here.

I have a working grep term which I want to use in vim.

It's simply grep "^#" malformed_file.tmp | grep '^.\{80\}$'; or in other words:

I want to have a search term in vim which jumps to the next line starting with # which is exactly 80 characters long, not longer.

How can I translate this grep stanza to a vim search?

It needs to be done in vim since what corrections need to be made to the following line depends on human input.

https://redd.it/1fy5uwe
@r_bash