How to delete the last blank line in a .txt file?

Hi;
I’m working on a noscript that’s supposed to remove the white spaces and empty lines from a txt file. On a Macbook.
So far, I’ve been able to do that with sed an a regex pattern.
The issue is that it keeps the last blank line in place.
For example, once edited, I’d like my document to show:

- x
- y
- z

and stop there.
Instead, I’m getting:

- x
- y
- z
[blank line here]

Would you know why that happens?
I’ve tried many variations of suggested stackoverflow “sed” solutions, but none of them has been helpful so far.

https://redd.it/1394kj1
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Replacing multiple spaces

Hi everyone.
So i have been trying to replace multiple (>2) whitspaces in a file with two dashes. --

I am trying this sed command. But it doesn't work.

 sed`s/[ ][ ]*/\-\-/g` 

Can anyone help?

Example

 Hi             Lokesh kumar             maxi 

Expected out

Hi--Lokesh kumar--maxi

https://redd.it/139e3dr
@r_bash

Finding the current cursor position in bash

The call for getting printed current row and col on screen are easy,(echo -e "^]]6n"), but it is harder to stuff the values into variables, so you can actually use them.

So, having other things to spend my time on, after a little while, I came by these two links, that seem okay for terminals in linux.

This way uses the ncurses tput command, which you should install anyways for this. Stack-exchange

The answer by Dennis Williamson in Stack Overlow post is more finicky but uses only bash, and, returns correct row/col positions for further use with ncurses.

https://redd.it/139hvju
@r_bash

assign fields parsed via awk; delimiter

Bash 5.1 on Linux Mint 21.1

i need to decode filenames always following this structure: Part1_Part2_Part3.wav
The delimiter is an underscore.

With the code field=$(echo "$file" | awk 'BEGIN{FS="_"} {print $3}' )" i only be successful, if there is an underscore behind Part3. Right now i add an underscore to all the files for the code to work. Is there another way?

https://redd.it/139kbnn
@r_bash

Creating a new variable from using grep on another variable

I am writing a noscript which enters a task into the taskwarrior app. The app response is "Created task number 114" (or any other number for that matter). I can catch that in a variable.

Now I want to use only the number (114) to use a a variable later (I can create a new task which is declared as dependent on task 114). According to what I have found already, this should work, but unfortunately does not:

Tasknumber=$(echo "$Response" | grep '[0-9\] {1,4}$')

when I echo $Tasknumber, it is empty.

Any tipps? Thank you

https://redd.it/139v7pb
@r_bash

Are fractional seconds in HISTTIMEFORMAT possible?

As the noscript says I'm interested whether or not it's possible to specify fractional seconds.

I already tried:

HISTTIMEFORMAT='%.3s '
HISTTIMEFORMAT='%s.%N '
HISTTIMEFORMAT='%s.%f '

It appears that it's not possible.

And I find that odd and dissatisfying, because I don't get "the issue" as why not.

That man page only says it must be in strftime format. GNU date accepts %N and bash's HISTTIMEFORMAT doesn't.

https://redd.it/139wiy9
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How do i create a large text file crawler which crawls and finds keywords and condition quicker than usual grep awk considering the log file size as 10-20gb .gz file of text. Is there a way?



https://redd.it/13adoww
@r_bash

Is there a way to remove the background of dialog command? Currently its blue but I want it as terminal default or like black.



https://redd.it/13adkik
@r_bash

Is there a way to use grep with wildcards?

Example

$file ./-* | grep "ASCII text" -w

./-file07: ASCII text
./-file09: Non-ISO extended-ASCII text, with no line terminators

I just want ./-file07. In a sql query it would look like

Select file from files where name like “ASCII%”

This would only return the files that names began with ASCII

Im assuming there is a way to accomplish this right?? Thanks

https://redd.it/13b2pmg
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For overthewire bandit level 14 nc is used to send password to localhost, if its correct it sends back “Correct!” with the next levels password. I am trying to replicate this but cant.

Solution is here: https://mayadevbe.me/posts/overthewire/bandit/level15/

This is how I tried to replicate it… I opened 2 terminals. In one terminal I started listening for inputs on port 1234. If the input matches “password” I wanted to send back “Success” but I cannot figure out how to send the response back and display it on the client terminal

Server

nc -l -p 1234 | grep "password" | xargs -I {} echo "Success”

Client

nc localhost 1234
> password

this is able to recognize when password is sent but the message is printed out server side. How can I get it to print out on the client side???

Thank you.

https://redd.it/13b961r
@r_bash

Remove Text Outside margins?

So basically I have a decent collection of PDF/ePub files that I’d like to strip out the header and footer info, like page number, chapter etc etc. so I can pass it through a text to speech generator, is there a reasonable way to accomplish this in a bash noscript? Maybe parameters so I can define the area to keep ?

https://redd.it/13bacau
@r_bash

Need help use AWK if then in a noscript

Good evening (EDT)

I am trying to write a short noscript that returns the last word of a file. This is pretty easy:

#!/bin/bash
sudo apt update &>/home/user/.config/polybar/modules/apt &&
cat /home/user/.config/polybar/modules/apt | awk 'END{print $1}'

(The word at the end of the file is how many APT packages need updating)

However, when everything is up to date, the noscript returns "All" as that is the first word of the last line of the temp file created in line 2 of the noscript.

What is a good way to return the first word of the last line UNLESS that word is "All" in which case "0" (or some other phrase) is returned?

Thank you!

https://redd.it/13b8cj0
@r_bash

What happens if I do kill -TERM 0

I know sending TERM to 0 will send TERM to ALL the process in current process group but will the following cause infinite loop?

trap "kill -TERM 0" TERM

./ child_process


I am trying to figure out the behaviour of current process after sending kill -TERM 0

https://redd.it/13bphhw
@r_bash

Is it true that bash/sh (or shell languages in general) were first designed to be used by end users and not programmers?

I don't know where I heard or read this first but I can't find any good source on it, is it true that shell languages were first designed to be used by Unix end users in the 70s-90s who didn't know much about programming?

https://redd.it/13bxtlp
@r_bash

How to close all previously running gnome terminals, and start up new ones? pkill doestn work.

Hi, i would really appreciate some help with a simple noscript. I have an autonomous robot running on ROS (robot operating system).


My task right now is this:
1. I have 6-7 terminals running at all times. At a certain point of an automated process (robot coming to dock), I want to close all running terminals
2. Run specific commands to launch robot processes

I have tried using pkill to close all terminals but when I try to run commands after that, it doesnt work. Could you point me in the right direction?

​

Thanks

https://redd.it/13bwqwb
@r_bash

Help with referencing a variable and dealing with quotes, escapes, and braces?

These are the source folders in an rsync command. It works as-is but I can't figure out how to put this in a variable and then refer to the variable instead. All on one line, it's:

>/Users/$USER/Library/./Mobile\\ Documents/com\~apple\~{Pages,Numbers,Keynote}/ /Users/$USER/./Documents/Folder\\ name

I tried putting it in a variable as

>SOURCE= "/Users/$USER/Library/./Mobile Documents/com\~apple\~{Pages,Numbers,Keynote}/ /Users/$USER/./Documents/Developer/Folder name"

And then referring to

>"${SOURCE}"

I also tried the variable reference without curly braces and without quotes, and adding an escape before the spaces in the variable. Nothing I've tried works. I get an error message that the folder can't be found. The error quotes both folder references together. I think my issue is properly handling spaces when inside a quote that defines a variable, and maybe the braces when in a variable.

My underlying goal is to have a variable that includes all the source folders, and then just refer to the variable in the rsync command.

https://redd.it/13c2br3
@r_bash

Amazing ssh banner for full node

https://github.com/st3b1t/Satoshi.motd

https://preview.redd.it/dzy6w8l3epya1.png?width=763&format=png&auto=webp&v=enabled&s=cd0cd3dc25fe4b15d9727c897255fd8ab426bc70

https://redd.it/13cagbp
@r_bash

Fish-like dirhistory (prevd/nextd) for Bash

Hello Bash users,

I while ago I came across this video extolling the virtue of Fish's Alt-Left and Alt-Right key-bindings.

Those binding provide a cd - experience on steroids, instead of being limited to just one level (back and forward between the current and last directory), Alt-Left (prevd) and Alt-Right (nextd) instead navigate the full directory stack of the current session.

Zsh via Oh My Zsh provides the Dirhistory plugin to mimic that functionality.

But what about Bash?

I could not find a solution, maybe someone has implemented it, but I could not find it, so I implemented my own solution which is this:

cd() {
local target="$@"
if [ -z "$target" ]; then
# Handle 'cd' without arguments; change to the $HOME directory.
target="$HOME"
fi

# Note, if the target directory is the same as the current directory
# do nothing since we don't want to needlessly populate the directory stack
# with repeat entries.
if [ "$target" != "$PWD" ]; then
\builtin pushd "$target" 1>/dev/null
fi
}

# Alt-Left: rotate back in the directory stack.
bind -x '"\C-x\C-p": "pushd +1 &>/dev/null"'
bind '"\e1;3D":"\C-x\C-p\n"'
# Alt-Right rotate forward in the directory stack.
bind -x '"\C-x\C-n": "pushd -0 &>/dev/null"'
bind '"\e[1;3C":"\C-x\C-n\n"'

We override `cd` to pushd and we then use `pushd` to rotate the directory rather than use `popd` which will eliminate item from the stack. We don't want to eliminate items since we may wish to go forward again, we want rotation.

The binding looks a bit ugly I agree, according to [this StackExchange thread it is the way to silently execute a binding; aka do not print out pushd +1 &>/dev/null in the command line. I use Control-p and Control-n intermediaries since I don't use those bindings in the command line. If there is a nicer way to do this, please pass it on.

But overall, not a lot of code to obtain Fish-like directory stack navigation.

If there are any issues let me know, otherwise enjoy.

https://redd.it/13cfbbp
@r_bash

Is there a difference in execution between executing a command and using an alias for the exact same command ?

I want to use a command semi often, so I put an alias for this command in my .bashrc but when I execute it, it throws an error that doesn't happen when I execute the command it is aliased directly.

I want to execute yt-dlp with a specific url in different directories, so I save the url in a "url.txt" file and execute the command

yt-dlp $(cat url.txt)

which works perfectly, but when I use the alias to the same command it can't read the url, is it the use of a subshell that isn't available in an alias ? would it be possible in a function ?

​

Also, unrelated, but to get the second to last line of a file, is there a better way than using

tail -n 2 foo | head -n 1

?

https://redd.it/13cwrib
@r_bash

Kube-dialog update

Hi, kube-dialog got an update! Edit cmd added to cronjobs. And filtering updated, you can filter by status info using a template like this '#...'! Extremely handy!


https://preview.redd.it/b839g6fuquya1.png?width=883&format=png&auto=webp&v=enabled&s=3074e400a90f1fc32c4f2c4091e2781f9f5944fd

https://redd.it/13d2dhw
@r_bash

Can anyone explain in English what these lines do?

I'm completely new to bash or Linux in general but have been using other languages many years ago so know the basics of strings etc.
I'm failing to understand these lines other than they are extracting something from one file and creating some variables. I can't find anything on -t or -p and I think "${1} might be an argument passed into this noscript. Other than that, I'm stumped.

`5 PREDICTION_START=\`/usr/bin/predict -t /home/bob/weather/predict/weather.tle -p "${1}" | head -1\``
`6 PREDICTION_END=\`/usr/bin/predict -t /home/bob/weather/predict/weather.tle -p "${1}" | tail -1\``
`7 MAXELEV=\`/usr/bin/predict -t /home/bob/weather/predict/weather.tle -p "${1}" | awk -v max=0 '{if($5>max){max=$5}}END{print max}'\``

https://redd.it/13eo6zr
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