Why can't I use !! in bash noscripts or in the bashrc ?

Ideally I would like be able to set an alias that does the same thing as !!, or call a noscript that does the same thing as !! . However i get "command not found" . The only way I am able to repeat a command is by directly typing !! into the prompt. Is there a way to get around this ?

https://redd.it/124vjzu
@r_bash

Trying to find hex in bin file

I'm trying to search a bin file for "1E FA 80 3E 00 B8 01 00 00 00"

I can find 1E

grep -obUaP "\x1E" "$file"

and I can find FA

grep -obUaP "\xFA" "$file"

But trying to find 2 bytes doesn't work:

grep -obUaP "\x1E\xFA" "$file"

I'm actually trying find and replace the 2 bytes that come after "1E FA 80 3E 00 B8 01 00 00 00".

https://redd.it/125d3up
@r_bash

Why can't the shell access the ssh authentication agent launched by the noscript?

I pieced together a simple noscript that allows me to backup my Windows 10 PC (using WSL) to my NAS which is running Ubuntu. I managed to get it working but during debugging one thing I found confusing was that after the noscript ran if I wanted to add another key to ssh-agent the shell could see ssh-agent running but it couldn't interact with it. (see below for console log)

I am aware that when I launch the noscript it creases a subprocess of the current shell but why did the last command I typed fail to add the key to the authentication agent? Are processes launched in a subprocess not accessible by the shell?

​

me@grimlock:\~$ cat backup2computron.sh#!/bin/bash

me@grimlock:\~$ cat backup2computron.sh

\#!/bin/bash

​

​

if [[ -n $(pidof ssh-agent) \]\]

then

echo "ssh-agent is already running"

else

eval `ssh-agent -s`

ssh-add /home/me/.ssh/grimlock_rsa_4096

fi

​

cp /mnt/c/Users/me/AppData/Local/Google/Chrome/User\\ Data/Default/Bookmarks /mnt/c/Users/me/Documents/data/backup

rsync -haP --append-verify --no-perms --omit-dir-times --delete -e "ssh -i /home/me/.ssh/grimlock_rsa_4096" /mnt/c/Users/me/Documents/data/* me@10.0.0.1:/mnt/dataPool/data/backup/

​

me@grimlock:\~$ ./backup2computron.sh

Agent pid 839

Identity added: /home/me/.ssh/grimlock_rsa_4096 (me@grimlock)

sending incremental file list

me@grimlock:\~$ pidof ssh-agent

839

me@grimlock:\~$ ssh-add /home/me/.ssh/id_ed25519

Could not open a connection to your authentication agent.

me@grimlock:\~$

https://redd.it/125iwsh
@r_bash

Writing haversine function in bash

I'm trying to convert the python haversine function [here:](https://stackoverflow.com/a/4913653)

def haversine(lon1, lat1, lon2, lat2):
# Calculate the great circle distance in kilometers between two points
# on the earth (specified in decimal degrees)

# convert decimal degrees to radians
lon1, lat1, lon2, lat2 = map(radians, [lon1, lat1, lon2, lat2])

# haversine formula
dlon = lon2 - lon1
dlat = lat2 - lat1
a = sin(dlat/2)**2 + cos(lat1) * cos(lat2) * sin(dlon/2)**2
c = 2 * asin(sqrt(a))
r = 6371 # Radius of earth in kilometers. Use 3956 for miles. Determines return value units.
return c * r

To pure bash. I know, I know, why? Just because really. Anyway I got this:

#!/bin/bash

# Haversine function implementation
# Usage: haversine lat1 lon1 lat2 lon2

# Convert degrees to radians
deg2rad() {
echo $(echo "scale=10; $1 * 0.017453292519943295" | bc -l)
}

# bc has arctan, but not arcsin so, stolen from http://advantage-bash.blogspot.com/2012/12/trignometry-calculator.html

asin() {
if (( $(echo "$1 == 1" | bc -l) ));then
echo "90"
elif (( $(echo "$1 < 1" | bc -l) ));then
echo "scale=3;a(sqrt((1/(1-($1^2)))-1))" | bc -l
elif (( $(echo "$1 > 1" | bc -l) ));then
echo "error"
fi
}

# Haversine formula
haversine() {
R=6371 # Earth radius in km
dLat=$(echo "$3 - $1" | bc -l)
dLon=$(echo "$4 - $2" | bc -l)
lat1=$(deg2rad $1)
lon1=$(deg2rad $2)
lat2=$(deg2rad $3)
lon2=$(deg2rad $4)

a=$(echo "scale=10; (s($dLat/2))^2 + c($lat1) * c($lat2) * (s($dLon/2))^2" | bc -l)
c=$(echo "scale=10; 2 * asin(sqrt($a))" | bc -l)
d=$(echo "scale=10; $R * $c" | bc -l)

echo $d
}

haversine $1 $2 $3 $4


Just some math. The problem I have when I run it with something like `haversine 22.70416 -118.29725 19.57834 -155.07947` I get an error that tells me `asin not defined` right near the end. It's defined right there, right above the haversine function. I'm not sure what it is I'm missing.

https://redd.it/125y1yk
@r_bash

program to print out biggest number from a set of numbers

i am trying to make a program to print out like:

How many numbers: 5

1

2

3

4

5

Largest number is 5

&#x200B;

So my question is, do I need to use like an array method for the set of numbers

https://redd.it/1260aue
@r_bash

How to check in bash if python noscript is running?

I use android (termux) scheduler to trigger following scheduler.sh

#!/data/data/com.termux/files/usr/bin/bash

# load EVs
source "$HOME/storage/shared/Books/AppsCfg/Termux/envfile"

python "$MEMS/Binv/noscripts/binvscheduler.py"

Most of the time it works great (according to schedule android triggers scheduler.sh which triggers binvscheduler.py noscript), but sometimes on device wake up binvscheduler.py gets double triggered. I added create lock file logic into python noscript and it catches 99% of double triggers except one case... (i can't even understand how it's possible. maybe somehow 2 binvscheduler.py run exactly same moment so python can't create lock file fast enough. Not sure)

Anyway, how do i check inside bash (in scheduler.sh) if binvscheduler.py is already running or not?

https://redd.it/12625u0
@r_bash

What is the meaning of ! -d

I'm sure this has been asked else where so sorry if so. But i'm with a collogue and we can't figure out what this is. Would any one happen to know Really appreciate ti!

https://redd.it/1263vrz
@r_bash

I couldn't find a way to check the difference between the current git branch and its parent so I decided to DIY

Hey everyone! As the noscript suggests, I created a small noscript to help me check the difference between my current branch and its parent by keeping a table that points to the parents. here is my repo

https://github.com/A-Siam/diffwatch

I am by no means a noscripting wizard so any suggestions or contribution is much appreciated.

Also, I don't know if my noscript is even a good idea :D if there is any good alternative to my hacky noscript please let me know.

cheers.

https://redd.it/1266mmd
@r_bash

How to delete a matching line and it's line break in a file

I have a .conf file where I use echo to append a line of text with a line break. But if I later want to remove the line I can't remove it and the line break.

To append the line to the end of file I use:

echo 'drive_db_test_url="127.0.0.1"' >> "$file"

Then I can remove the line with the following but it leaves the line break:

sed -i 's/drive_db_test_url=\"127\.0\.0\.1\"//' "$file"

I've tried things like but they don't work:

sed -irz 's/drive_db_test_url=\"127\.0\.0\.1\"\n//' "$file"

And I've seen all sorts of ways to remove all line breaks in a file, using tr, sed or awk but I don't want to remove all line breaks.

https://redd.it/126au5r
@r_bash

2>&1

You know what gets my head in?

In Linux/Bash when we want something to run in the background we would do something like this: ./yourCommand > /dev/null 2>&1 &

I am taking issue with 2>&1. "&1" refers to a variable as we can see by the "&", the standard bash variable "standard output" so far so good :> all makes sense.

But the "2" here refers to another variable "standard error" why then we don't write &2>&1?

Would ./yourCommand > /dev/null 2>1 & be valid syntax and work?

https://redd.it/126ogzm
@r_bash

I made simple IPTV player in bash

https://github.com/shahin8r/iptv

With support for your own M3U playlists.

&#x200B;

https://i.redd.it/6pcs7dughwqa1.gif

https://redd.it/126qzeh
@r_bash

I made a simple IPTV player in bash with M3U support
https://redd.it/126rx9w
@r_bash

A helper function to tell if a noscript is sourced?

I write a fair amount of noscripts and I often have strong opinions on whether those noscripts should be sourced or executed. It's usually because I don't want to screw over future me because I've written a noscript that is a little aggressive with the environment.

For those noscripts I have a block of code I run:

(return 0 2>/dev/null) && sourced=1 || sourced=0
if [[ $sourced -ne 0 ]]; then
echo "Don't source this noscript. Run it directly"
return 1
fi

I also hate copy and pasted code, but because this relies on the behavior return has depending on if a noscript is sourced or executed, I can't really put this is a helper function and call that helper function. Instead I do this (mildly crazy) thing where I have a bunch of noscripts stored in variables and then I just eval those in the noscript.


So I have a utiltiy noscript with something like:

# shellcheck disable=SC2034
BASH_COMMON_SCRIPT_UNSOURCEABLE=$(cat <<'EOM'
(return 0 2>/dev/null) && sourced=1 || sourced=0
if [[ $sourced -ne 0 ]]; then
echo "Don't source this noscript. Run it directly"
return 1
fi
EOM
)

And then I use this in a noscript kinda like:

CONFIGROOT_DIR_SCRIPT="$( cd "$( dirname "$( readlink -f "${BASH_SOURCE[0]}" )" )" >/dev/null 2>&1 && git rev-parse --show-toplevel 2>/dev/null )"
if [ -f "${CONFIGROOT_DIR_SCRIPT}/util/noscripts_as_variables.sh" ]; then
# shellcheck disable=SC1091
source "${CONFIGROOT_DIR_SCRIPT}/util/noscripts_as_variables.sh"
fi
eval "${BASH_COMMON_SCRIPT_UNSOURCEABLE}"

And yes I'm aware of the perils of eval'ing an env var.


Is it possible to do this in a more sensible way?

https://redd.it/126tv9y
@r_bash

CSV to variables

I'm trying to parse a csv to variables to use it in "update all wordpress/nextcloud/..." noscripts

The CSV looks like this:

nicename,application,directory
blog1,wordpress,/var/www/wordpress1
blog2,wordpress,/var/www/wordpress2
cloud,nextcloud,/var/www/nextcloud

How do i parse these into variables like $blog1.directory (using the nicename)?

https://redd.it/126rxvi
@r_bash

Need help creating a simple loading noscript

Hi everyone! I am currently creating a noscript that saves data to a file, and another one that loads that data. I have already create the saving part, but now I need to figure out the loading part. I need to load the even lines as "arg1(number of line)" and "arg2(number of line)". How can i do it?

https://redd.it/126xl55
@r_bash

Aiyu, a set of shell functions that wraps around all major AI projects and interconnects them. It's a shell function!

https://github.com/GabrieleRisso/aiyu

https:\/\/github.com\/GabrieleRisso\/aiyu

https://redd.it/126xde6
@r_bash

Learning bash is so frustrating

Can you recommend to me any site more preferably a pdf tutorial for bash.
Thank you.

https://redd.it/1272uv3
@r_bash

Color schemes in Micro

Hello, I am just wondering how to change the color scheme of micro text editor in a bash noscript.

the command to change the color scheme is

^e set colorscheme "colorscheme"

https://redd.it/1279ifv
@r_bash

Made a noscript manager for non-savvy users

Hey there,

&#x200B;

I work with a lot of field techs, skill levels on computers vary. We have a bunch of various noscripts that we need the techs to run, but some have a hard time staying organized.


I made this so that there is a single folder, where all the noscripts reside. You only have to open this single "app" if you call it that. From there, they can run multiple noscripts with an interface.

&#x200B;

I couldn't really find anything like this, so I made it.

&#x200B;

Thoughts on improving? Also feel free to use it.

&#x200B;

https://github.com/kylezwhite/slector

https://redd.it/127f4tk
@r_bash

Sshto update

Hi, sshto got an update, I've added quick filter!)
Due to lack of buttons in dialog I had to add it to the list.


https://preview.redd.it/wz0q5bnq03ra1.png?width=861&format=png&auto=webp&v=enabled&s=beb7d077864954f90e22aab7a4d148e49ae35f4a

https://redd.it/127mqo0
@r_bash

Question about calls with relative paths

The following is a call with an absolute path specification that works for me. This call, opens the file samplefile with the editor xed:

xed /a/b/c/d/e/f/g/samplefile.txt

Suppose I open a terminal and type the following:

cd /a/b/c/d

How would I then have to open the text file with the editor xed from this position with a relative specification. For example the following call I tried seems to be wrong here:

./e/f/g/samplefile.txt

https://redd.it/12809zu
@r_bash