Making a matrix

Hey, everyone! I'm still fairly new to bash and don't exactly know how to solve this exercise we received for studying. If anyone could help me, I would really appreciate that. Here's the text:
You are tasked to create a simple program that emulates a cinema ticket reservation system for a cinema with a single screen and 100 seats organised in a 10x10 grid.
The seating arrangement should be presented to the user as a 10x10 grid. Each seat is identified by its position in the grid (e.g. the first seat is at position 0,0 and the last seat is position 9,9). For visual representation, the program should use 'A' for available seats and '_' for reserved seats.
The program should begin by displaying a greeting message to the user and the current seating map, where all seats are initially available. It should then prompt the user to enter a seat number to reserve. After the user provides a valid seat number, the program should reserve that seat and display the updated seating map. If the seat is already reserved, the program should inform the user and prompt them to choose another seat.
After reserving a seat and showing the updated seating map, the program should ask the user whether they want to reserve another seat. If the user decides to continue, the program should repeat the reservation process. Otherwise, it should end with a closing message.

Thanks in advance to anyone who's willing to help me with this exercise.

https://redd.it/17wj6s0
@r_bash

Using an INT trap to dynamically debug a running noscript

I came up with a way to using `trap ... INT` to help dynamically debug a noscript/function as it is running. I find it quite useful, and figured others on /r/bash might as well.

Set the following trap at the start of the functions/noscripts you want this functionality enabled on:

trap 'printf '"'"'%s\n'"'"' "" "press [a] to Abort (exit)" "press [u] to Unset INT trap (makes <ctrl> + <c> work normally again)" "press [x] to eXecute a command" "press [p] to print the Present working directory" "press [i] to print Information about what caller/function/line/command is currently running" "press [d] / [D] to [start] (set -xv) / to [stop] (set +xv) printing Debug output to stderr" "press [v] / [V] to write Vars (declare -p) to [stderr] / to [file (${PWD}/.vars)]" "press [e] / [E] to write Environment (env) to [stderr] / to [file (${PWD}/.env)]" "press anything else to continue" >&2;
read -r -n 1;
case "$REPLY" in
a) exit ;;
u) trap - INT ;;
x) if [[ $USER == root ]] && [[ ${SUDO_USER} ]] && ! [[ ${SUDO_USER} == root ]] && type -a su &>/dev/null; then su -p "${SUDO_USER}" < <(read -r && echo "$REPLY"); elif ! [[ $USER == root ]]; then source <(read -r && echo "$REPLY"); else echo "for security running generic commands as root is not allowed" >&2; fi ;;
p) echo "$PWD" ;;
i) echo; [[ $FUNCNAME ]] && printf '"'"'function: %s\n'"'"' "$FUNCNAME" >&2; printf '"'"'caller : %s\n'"'"' "$0" >&2; [[ $BASH_LINENO ]] && printf '"'"'line : %s\n'"'"' "${BASH_LINENO}" >&2; printf '"'"'command : %s\n'"'"' "${BASH_COMMAND}" >&2 ;;
d) set -xv ;;
D) set +xv ;;
v) declare -p >&2 ;;
V) declare -p >"${PWD}"/.vars ;;
e) env >&2 ;;
E) env >"${PWD}"/.env ;;
esac' INT


This will make it so that when you press `<ctrl>` + `<c>` the following menu appears:

press [a] to Abort (exit)
press [u] to Unset INT trap (makes <ctrl> + <c> work normally again)
press [x] to eXecute a command
press [p] to print the Present working directory
press [i] to print Information about what caller/function/line/command is currently running
press [d] / [D] to [start] (set -xv) / to [stop] (set +xv) printing Debug output to stderr
press [v] / [V] to write Vars (declare -p) to [stderr] / to [file ($PWD}/.vars)]
press [e] / [E] to write Environment (env) to [stderr] / to [file ($PWD}/.env)]
press anything else to continue

The shell will then read 1 character and if it is one of the ones listed above it will run the corresponding action in the `case` statement from the `trap ... INT` definition. I chose these actions feeling that they might be of use when debugging a noscript, though of course you can modify/add/remove possible actions by redefining the trap.

***

One note regarding the "press [x] to eXecute a command" action:

As it is implemented above, it will not execute commands as root. If allowed to run commands as root, it would allow someone to hit `<ctrl>` + `<c>` on a noscript run with `sudo` and then execute generic commands (outside the scope of what the noscript was intended to do) as root. Which is dangerous.

If run as root and you press `x` at the INT trap menu it will try and run your command as the (non-root) `$SUDO_USER` (the user you ran `sudo` from) using `su`. Unfortunately, this runs the command in a subshell, meaning you cannot use it to modify any parameters of the running noscript, which limits its usefulness.

If anyone knows how to run a command in the current (root) shell as a non-root user let me know and ill incorporate it. If you are OK with the security risks of running generic commands as root from the trap menu you can replace the `case` statement's definition for `x` with

x) source <(read -r && echo "$REPLY") ;;

https://redd.it/17wqep9
@r_bash

any tips why its not working?



if [[ $current_url != "${NGROK_REMOTE_URL}"  \]\];
then
curl -s -X POST "https://api.telegram.org/botapi/sendMessage" -d "chat_id=secret" -d text=${NGROK_REMOTE_URL}
current_url=${NGROK_REMOTE_URL}
fi

https://redd.it/17wtqme
@r_bash

Does anyone have a clue how to do this

Script 4: The server that hosts the images that you process with your previous shell noscript has been having connectivity problems. You want to write a shell noscript named checkserver.sh that you can schedule to run at night to ping the server and capture the results in a file. ping is a command to send packets to another computer to verify you can connect to it. Your noscript should take the IP address of the server as a parameter. For testing purposes, you may use 173.255.195.185. Your noscript should ping the server 10 times, save the output in a file and quit. The output file should include the date and time the ping was executed.

https://redd.it/17wxyau
@r_bash

New to bash and can't figure out array items

I have been beating my head against a wall about this for longer than I care to admit and am looking for a clue.

I am pulling all my budget names from AWS and storing them into a variable:

`budgets=$(aws budgets describe-budgets --account-id "$ACCOUNT_ID" | jq '.Budgets[].BudgetName')`

One big string that looks like this:

`"Market Accounts" "Scratch account" "DataScience Accounts" "Infrastructure Accounts" "Networking Accounts"` etc..

so I convert it to an array so I can use the items individually:

`budgets=($budgets)`

but when I run it through a for loop:

`for budget in "${budgets[@]}"; do echo $budget; done`

It doesn't treat the quoted groups as items and treats every space as a delimiter.

So I get this output for `echo "${budgets[0]}"`

`"Market`

but my desired output is:

`"Market Accounts"`

Full snippet:

budgets=$(aws budgets describe-budgets --account-id "$ACCOUNT_ID" | jq '.Budgets[].BudgetName')
budgets=($budgets)
for budget in "${budgets[@]}"; do echo $budget; done

It has to be simpler that all the things I have tried. Any help is greatly appreciated.

https://redd.it/17x4fsh
@r_bash

Many of my functions are not recognised by GitHub as functions

I'm wondering if there's something wrong with the way I format my functions in bash. They work just fine in bash. But GitHub doesn't recognise many of them as functions.

GitHub's Symbols panel only lists 7 of the noscript's 21 functions. https://i.imgur.com/njBUl8J.png

Notepad++ shows all 21 functions in it's Function List. https://i.imgur.com/OxUxXWw.png

I had a similar issue with Notepad++ when the first line in the function was a comment. I fixed that by adding a space after the {

The bash noscript is here: https://github.com/007revad/Synology\_HDD\_db/blob/develop/syno\_hdd\_db.sh

Is there anything I can change in my bash noscript that will make GitHub recognise all of my functions as functions?

&#x200B;

https://redd.it/17x7fp8
@r_bash

Wayland noscript that is equivalent to x11

Hi, I wrote a noscript for browser functionality. Is it possible to rewrite it to wayland? Thanks in advance!

Basically, what this noscript does:

If browser isn't open, it opens it

If browser is open, but not active, it activates it

If more than one browser window is open, it cycles between them

&#x200B;

\#!/bin/bash

\#Needs wmctrl ,libnotify-bin, noscript x11 only

&#x200B;

defaultBrowser=$(xdg-settings get default-web-browser -eq)

if [ "$defaultBrowser" = "brave-browser.desktop" \]; then

findName="Brave"

launchName="brave-browser"

fi

&#x200B;

if [ "$defaultBrowser" = "firefox_firefox.desktop" \]; then

findName="Firefox"

launchName="firefox"

fi

OUTPUT=$(wmctrl -l | awk '{print $1, $NF}' | grep $findName | awk '{print $1}')

&#x200B;

a=($(echo "$OUTPUT" | tr ' ' '\\n'))

aSize=${#a[@\]}

&#x200B;

\# Check if array size is 0

if [ "$aSize" -eq 0 \]; then

$launchName &

notify-send -t 800 "Launching: $findName"

exit

elif [ "$aSize" -eq 1 \]; then

wmctrl -ia "${a[0\]}"

exit

elif [[ -z $(wmctrl -lp | grep "$(xprop -root | grep _NET_ACTIVE_WINDOW | head -1 | awk '{print $5}' | sed 's/,//' | sed 's/\^0x/0x0/')" | grep $findName) \]\]; then

wmctrl -ia "${a[0\]}"

exit

else

activeWindowID=$(wmctrl -lp | grep "$(xprop -root | grep _NET_ACTIVE_WINDOW | head -1 | \\

awk '{print $5}' | sed 's/,//' | sed 's/\^0x/0x0/')" | awk '{print $1}')

&#x200B;

for i in "${!a[@\]}"; do

if [ "${a[i\]}" == "$activeWindowID" \]; then

index="$i"

if [ "$index" -eq "$((aSize - 1))" \]; then

index="0"

else

((index++))

fi

wmctrl -ia "${a[$index\]}"

exit

fi

done

fi

https://redd.it/17xebi9
@r_bash

HELP! Bash noscript wilding. Even GPT is stumped.

Hi there,

I've been modifying this noscript so that it uses grim and slurp to work on wayland. Now I've hit the road block. The output of the program (After modification) is:

Selected geometry: 1118,285 528x656
Screenshot command: grim -g "1118,285 528x656" /home/baighack3rss/Pictures/Screenshots\/1700230454.png
invalid geometry
Command exit status: 1

Now here is the interesting part. If I just copy the screenshot command and run it in the terminal it works but in the noscript it's an invalid geometry.

I've attached the noscript to this hastebin.

Thanks in advance!!

https://redd.it/17xg4m2
@r_bash

HELP! Bash noscript wilding. Even GPT is stumped.

Hi there,

I've been modifying this noscript so that it uses grim and slurp to work on wayland. Now I've hit the road block. The output of the program (After modification) is:

Selected geometry: 1118,285 528x656
Screenshot command: grim -g "1118,285 528x656" /home/baighack3rss/Pictures/Screenshots\/1700230454.png
invalid geometry
Command exit status: 1

Now here is the interesting part. If I just copy the screenshot command and run it in the terminal it works but in the noscript it's an invalid geometry.

I've attached the noscript to this hastebin.

Thanks in advance!!

https://redd.it/17xg4k2
@r_bash

Help! I am horrible at this.

I am not great at bash (or any of the others), to the point where I’m not sure what the proper names for things are. If anyone can help I would very much appreciate it!

I am trying to convert a column of a csv (list of protein names) to a list to grep matching lines from a bunch of other csvs. What I want are the names of the proteins in column A to become a string list like: Protein A\|Protein B\|Protein C\|Protein D\|

I have the noscript to run the grep function, all I need to know is if there is a way to get the 300 protein names into the above format. Thank you for any help!!!

https://redd.it/17y5q8r
@r_bash

grep not finding anything in csv log file

Hi,

I have a CSV file that when I run the grep command, it doesn't find any matches in it. However, when I copy the text from a specific cell (eg: Message in column) of the CSV into another TXT file, grep works perfectly searching for the word "TEST".

I've read about using the param -a with grep but it didn't work.

Grep man explanation:

-a, --text Process a binary file as if it were text; this is equivalent to the --binary-files=text option.

Notes: when I do cat mylog.log.csv it doesn't appear to be a comma separated csv, I think it's separated by tabs. When I open it using excel it shows all ordered by columns.

&#x200B;

If you print cat mylog.log.csv it outputs like this

��TimeStamp Component Severity Message Source Type Message Thread ID Source File Name Source Line Instance ID Msg ID App Area Business Obj BO ID Customized
2023-11-08 13:31:11.840349 Sql Note I Tec "ExecuteQueryDirect #Duration=911 #Fetched=7 #Query select columnname, datatypename, ISNULLABLE, length, length as precision, scale from sys.viewcolumns where schemaname = 'SYSBIC' and viewname = 'sap.test.TESTVIEW/TESTVIEW' order by position #Status=1 # #" TID=5956 ../Infrastructure/Engines/DBM/DBMCDataBase.cpp 10110

I read it could be something related to \\r so people recommended to use cat -A and it outputs weird formatting like this

M-^?M-~T^@i^@m^@e^@S^@t^@a^@m^@p^@^I^@ ^@C^@o^@m^@p^@o^@n^@e^@n^@t^@^I^@ ^@S^@e^@v^@e^@r^@i^@t^@y^@^I^@ ^@M^@e^@s^@s^@a^@g^@e^@ ^@S^@o^@u^@r^@c^@e^@^I^@ ^@T^@y^@p^@e^@^I^@ ^@M^@e^@s^@s^@a^@g^@e^@^I^@ ^@T^@h^@r^@e^@a^@d^@ ^@I^@D^@^I^@ ^@S^@o^@u^@r^@c^@e^@ ^@F^@i^@l^@e^@ ^@N^@a^@m^@e^@^I^@ ^@S^@o^@u^@r^@c^@e^@ ^@L^@i^@n^@e^@^I^@ ^@I^@n^@s^@t^@a^@n^@c^@e^@ ^@I^@D^@^I^@ ^@M^@s^@g^@ ^@I^@D^@^I^@ ^@A^@p^@p^@ ^@A^@r^@e^@a^@^I^@ ^@B^@u^@s^@i^@n^@e^@s^@s^@ ^@O^@b^@j^@^I^@ ^@B^@O^@ ^@I^@D^@^I^@ ^@C^@u^@s^@t^@o^@m^@i^@z^@e^@d^@^M^@$

Example of some columns in log csv file:

|TimeStamp|Message|
|:-|:-|
|2023-11-08 13:31:11.865258|static void B1SLogHelper::Log(IHttpResponse*, const char*): === Response Detail === status:200 content-type:application/json;odata.metadata=minimal;charset=utf-8 content: { "@odata.context" : "https://an_endpoint:50000/b1s/v1/sml.svc/$metadata#TEST_VIEW", "value" : [ { "ItemCode" : "111111111111", "ItemName" : "TEST_VIEW", "id__" : 111 }, \], "@odata.nextLink" : "TEST_VIEW?$orderby=ItemName%20asc&$skip=5400" } # #|

Link to download or check the csv file https://drive.google.com/file/d/1uCS4Wmo\_ROrFDZ6JQcgVEISyRfW7S682/view?usp=sharing

https://redd.it/17yes57
@r_bash

shopt doesn't set/unset inside an if-block

I have a helper noscript that I use every day... until today, when it started throwing syntax errors. I haven't changed my bash version nor the noscript in at least two weeks. I managed to narrow it down to `shopt -s extglob` not setting extglob when inside an if-block. What's even weirder is: none of the lines before that extglob use are launched, but all the lines outside the if-block are launched, so the "syntax error" is happening during runtime instead of at the start like I'd expect.

* why does `shopt -s` inside an if-block not set a shell option?
* why the "syntax error" after already executing some of the lines of the noscript?
* (probably unanswerable) why did this fail today when I haven't changed bash nor the noscript in weeks?

EDIT: I can't do code blocks in the starting textpost; can't use \`\`\`, \`\`\`bash nor four-spaces, I'll have to post it as a comment below.

https://redd.it/17yp7xn
@r_bash

How do you capture the values of pblack and t inside a variable from this ffmpeg command?

Normally when you run this command from the terminal, it would give you output as follows

ffmpeg -i "video.mkv" -r 1 -loop 1 -i $HOME/test.png -an -filtercomplex "blend=difference:shortest=1,blackframe=95:32" -f null -

[Parsedblackframe1 @ 0x6000013880b0] frame:15168 pblack:80 pts:252800 t:252.800000 type:P lastkeyframe:15000
Parsed_blackframe_1 @ 0x6000013880b0 frame:15169 pblack:81 pts:252817 t:252.817000 type:B lastkeyframe:15000

But lets say I wanted to run this from a bash noscript and extract the values of pblack and t in a json array like this \[\[80, 252.8\], \[81, 252.817\]\] what do I do?
I am assuming bash doesnt support array inside array

**This is what I tried and it does not work**

vals=ffmpeg -i "video.mkv" -r 1 -loop 1 -i $HOME/test.png -an -filtercomplex "blend=difference:shortest=1,blackframe=95:32" -f null - 2>&1 | grep blackframe | sed 's/.pblack\:\(.\)/\1/'


&#x200B;

https://redd.it/17yscy2
@r_bash

Simple iterate through a directory to delete matched files not working

Hello,

I am simply trying to delete files in a directory that would match. However, wildcards are not working as expected when there is more than one match (`nf-flow` `nf-log` , etc.):

for MODULES in ppp pppoe nf-* nfnetlink nft-* *usb-core *usb2 *usb-ehci; do
if test -e /etc/modules.d/$MODULES; then
rm /etc/modules.d/$MODULES
fi
done

The wildcard errors with `unknown operand`

I have tried:

redirecting to > `/dev/null 2>&1` as well as `[[ test -e /etc/modules.d/$MODULES ]]` to recognize the wildcard but it still errors with `unknown operand`.

Stumped.

https://redd.it/17z2cyb
@r_bash

read-ing and process substitution (named pipes?), but simpler?

Hi!

So, this is working fine (as expected, for me). But it bothers me to have an echo there for some reason. Is there a cleaner way? Some way to read straight from a variable?

$ data="1 2 3"
$ read x y z tail < <(echo $data)
$ echo $x $y $z
1 2 3

Also, this doesnt work. I guess its because 'read' is an internal command and doesnt have a stdin "of its own"? Also, that doesnt get rid of the echo anyway:)

$ echo $data | read x y z tail
$ echo $x $y $z
<blank>

And just for kicks i tried this, but had to ctrl-c my way out of it. Longshot anyway.

$ read -i "$data" x y z tail
^C

&#x200B;

https://redd.it/17zau5s
@r_bash

Trying to figure out how to implement a specific operation on bash arrays as efficiently as possible

So, say I have an array `A` that looks like the following:

A=(a$'\n' 'b c'$'\n' d e$'\n' f$'\n') #note: the "real" A typically has 512 elements

Notice that all elements end in a newline except for one: `d`

The goal here is to identify any elements that do NOT end with a newline and combine them with the following element, transforming A to

A=(a$'\n' 'b c'$'\n' de$'\n' f$'\n') #note: every element now ends in a newline.

It is worth noting that

1. This could occur at any element in the array (except for the last element)
2. The chances of this occurring are very slim. Itll happen on average once every 200,000 or so elements, so out of every 4000-ish `A` arrays one will have this.
3. While not 100% required, a pure-bash solution is much preferred over solutions that depend on external binaries.

My best solution so far is

IFS=
A[-1]="${A[-1]%$'\n')"
mapfile A <<<"${A[*]}"

`"${A[*]}"` prints each element of `A` separated by the 1st character of IFS, which is nothing meaning no separation. The newlines at the end of each element break it up for `mapfile` to read, and by omitting the `-t` flag mapfile keeps the newlines. You have to remove the final newline or else you add a single empty element to the end. This works, but increases the overall runtime of the code it is a part of by 50% or more (depending on the specific workload).

Any Ideas? Thanks in advance.

***

Information about the actual code and the actual issue that inspired this post is below.

[This](https://github.com/jkool702/forkrun/blob/testing-mySplit/mySplit.bash) is the actual code it is going in. I need this to deal with a weird issue I've encountered related to reading and writing to the same file at the same time. To be honest I dont understand why this issue is happening, so if anyone has an idea I'm all ears.

The code provides `xargs`-like functionality for parallelizing loops (only is faster). It writes/appends stdin to a tmpfile (on `/dev/shm`) with one background process, and reads data from the beginning of this file with another background process (well several other background processes, but only one is reading at a given time). This gets around "reading 1 byte at a time from a pipe", but because data can be read faster than it can be written the reading process occasionally "catches up" to the writing one, causing it to think it hit an EOF and you get a partial read line.

To correct for this, I run `mapfile` without the `-t` flag and check if the last element ends with a newline, and if not I keep reading until I hit one and then append the data onto `A[-1]`. Which works 100% reliably....for `A[-1]`

The weird issue that I dont fully understand is that in 1 line out of every 200,000 or so, mapfile splits a seemingly random line in half for seemingly no reason. It is almost like mapfile hits an EOF but instead of stopping and returning a partial line in `A[-1]` it just keeps going, in effect splitting the line into 2 array indices (the first of which does not end with a newline). Hense this question on how to efficiently deal with this.

https://redd.it/17zchsq
@r_bash

How do you convince your team to use logrotate?

I know this will sound stupid but we are using find with combination with exec command instead of logrotate to find the log files and delete it. It's not like we've been using it for a long time, I just put them few weeks ago. Because they hesitated to use logrotate which they didn't really know well.

There is 1 team member whose decision is important and I've informed him about this issue(to learn this)....


I'm not hopeful he'll get time to learn because he is very busy guy.

https://redd.it/17zjiot
@r_bash

how do I assign sed -E 's/."url":"([^"])./\1/' to b named variable in bash

how to do

b=" sed -E 's/.\"url":"([\^"\]*).*/\\1/' "

&#x200B;

it is showing errors like

&#x200B;

b="sed -E 's/.*"url":"([\^"\]*).*/\\1/'"

∙

∙

∙

∙

∙

&#x200B;

&#x200B;

these empty spaces

&#x200B;

what should i do now

https://redd.it/17ztwr8
@r_bash

Removing noscript/header bar from terminal

I'm using i3 on both desktop and laptop, I searched for different solutions on removing a noscript/header bar (whichever you call it, the bar with the "File Edit View Search Terminal Help" buttons) some of them being, adding these lines to my i3 config:

default_border pixel 1 #or 0

default_floating_border pixel 1 #or 0

or just

new_window pixel1

With no avail. The border on my pc still persists and with them here, i3 doesn't notify of an error with the config file. On the other note, I remember adding a line to crontab -e on my laptop (and later removing it) which seems to have done the trick. I rambled through the browsing history but couldn't find the site from which I copied the line.

I even tried straight up scp-ing the i3/config and picom.conf files from the other machine which didn't fix the issue.

&#x200B;

https://redd.it/180bcqs
@r_bash

Using sed to replace mismatched characters

I'm looking to contribute to an open source project, where I noticed that it prints commands like this:

<command>'

Where inside the echoed string, a backtick is being matched with a single quote.

I checked the bash noscript, and this is how it's coded. First off - is this a mistake, or just a formatting error in my terminal?

So anyway, I used grep to find all instances of \ and luckily the codebase is not that big, so I could manually check which are being closed by a single quote.

I now want to use sed to replace the single quotes with matching ` in each bash noscript, but I can't get the right pattern.

The closest I got was being able to replace all single quotes with a `, but obviously I only want it where it's mismatched.

Is sed appropriate for this?

I'm ripping my hair out trying to learn the way to do it with the CLI instead of just writing a Python noscript.

Any pointers for how I could do this?

I'm on MacOS btw, so it's BSD sed. I've tried looking at the man pages and reading up online, but it's kinda confusing to me.

https://redd.it/180fncv
@r_bash

confusing difference in behaviour between bash test and [ ]

Hi all,

it seems I found a difference in the behaviour of the bash builtin test and [[.

$ touch foobar
$ if [ -e foo* ] ; then echo found ; fi
$ if [ -e "foo*" ] ; then echo found ; fi
$ if test -e foo ; then echo found ; fi
found
$ if test -e "foo" ; then echo found ; fi
$ type test
test is a shell builtin
$ type [
[[ is a shell keyword
$ bash --version
GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Apparently `[[` doesn't expand wildcards. If I got the docs right it should behave like `test` with additional operators to combine expressions, so this surprised me.

Is this expected or a weird bug/edge case? I'm just trying to understand, the `test` solution if fine for my needs.

Thx

[https://redd.it/180lnb2
@r_bash