Save result of echo command in a variable

This is a very basic question, but I am new to bash noscripting. In the code snippet below, I am trying to extract something from a file and save it to a variable. What I have shown in the first echo command is working correctly. Instead of echoing it, I want to save it to a variable. The stuff below that is not working, I feel like maybe I am missing brackets or have the $ in the wrong place. Thanks in advance for your help! Sorry about the bad formatting, I am posting from my phone.

#!/bin/bash

header_file="../../build.vivado/output/headers/axi_gp_header.vh"

# Extract the 3rd word (reg value) from the line that contains the word "DIAGNOSTICS":

echo $(grep "DIAGNOSTICS" $header_file) | cut -d " " -f 3


# This does not print the same thing as above:

REG_VALUE=$((grep "DIAGNOSTICS" $header_file) | cut -d " " -f 3)
echo $REG_VALUE

https://redd.it/yxtsx7
@r_bash

Bash - Renaming text file names based on word count

I am new to bash and have been struggling to figure this problem out. I have been trying to figure out how to go through a directory that contains all text file, sort and rename each text file according to their word count. I am trying to rename them 1.txt 2.txt 3.txt etc. 1.txt being the file with the least amount of words.

i=1
wc -w ./test1/txt | sort -n |
for files in./test1/txt; do
mv "$files" "./test1/$i.txt"
let i++
done;

This would rename the files 1,2,3.txt etc but it wont be in order of word count.

​

Thanks!

https://redd.it/yxw1nc
@r_bash

There seems to be a ghost in my array.

Here's the noscript:

get_names() { sudo virsh list --all | sed 1,2d | tr -s ' ' | cut -d ' ' -f 3 }

mapfile -t names < <( get_names )

printf '%s\\n' "${names[@\]}"; printf '%s\\n' "${#names[@\]}"

exit

There should be 5 elements in $names, but the noscript says there are 6. I manually the edits to virsh list output and they seem fine. I even rewrote the edits from the original noscript, posted a few days ago. I tested with a simple array, where I fed it the elements, so I know my computer can count ;-)

Any help?

https://redd.it/yxxvuu
@r_bash

Confused about desktop entry (.desktop) not making executable visible under App Launcher

Hi there,

I have:

added this line to `.bashrc` to append the directory 'Portables' to variable `$PATH`:

&#x200B;

export PATH=$PATH:/home/abc-pc/Portables

&#x200B;

applied this code from the terminal:

&#x200B;

source ~/.bashrc

copied the executable 'xyz' (an AppImage without extension) to 'Portables' with associated `xyz.desktop` and `xyz.png` files placed into `~/.local/share/applications` and `~/.local/share/icons`, respectively.
xyz.desktop contains these lines:

&#x200B;

Exec=xyz %f
Icon=xyz

The program runs okay from the terminal by just typing $ xyz, not $ ./xyz, which I presume means the system recognises the directory path inserted into `.bashrc`.

Question: Why doesn't the program icon show under the Application Launcher? It does, however, when I type in the full path to the program directory inside xyz.desktop. Although I thought that appending the path to $PATH was enough for the executable to be recognised by simply Exec=xyz (no full path, no file extension).

Thank you!

https://redd.it/yy2vsg
@r_bash

Incrementing variable names?

I have a select that I would like to use for assigning values to 4 different variables, a1, a2, a3 and a4. Is there something I could use for this, like

b=1
select a$b in c d e f
do
$((b++))
done

, but that actually works? Preferably something that uses no more selects than I already have, and not a bunch of nested ifs?

(If the answer is no, this is not possible with only one select and no nested ifs, feel free to let me know.)

https://redd.it/yy2ryt
@r_bash

how to make favicon and change the name of my website? (on replit)



https://redd.it/yy89uq
@r_bash

What color scheme do you use for LS_COLORS?

Are there any specific elements of color scheming that you find particularly useful?

https://redd.it/yy7oyb
@r_bash

Noob Attempts to write a bash noscript

So, I have been attempting to write a bash noscript, but I don't entirely know what I am doing. I have tried to test out what others have suggested I use/change, but everything in my vm seems to not to see them. I don't know if it changes anything, but the bash noscript is running in vi on a ubuntu console. Anyway, to the actual noscript.

"#"!/bin/bash -x
echo 'Enter the Directory: '
read dd

#This section serves to test if the input is a directory. Following the test, it will resound with a yes or a no.

if -d $dd
then

#If yes, then it will then check if it has a file with the above name. If it does not, it will ask if the person wants it to be created.

echo '$dd is valid directory and it. exists. '
if test -f '$dd'; then
echo '$dd file exists.'
else
read YN
echo '$dd file does not exist. Do you want to create it Y/N? $YN'
#This line below confuses me, but that is because I don't know what is going on.
if [ "$YN" =~ ^(no|No|NO|n|N)$ ] ; then
echo 'File will not be created.'
else
echo 'File will be created.'
touch $dd
fi
fi
else
#It is then suppose to do the same as above, but with a directory instead.
echo '$directory does not exist. Do you want to create it Y/N? $YN'
if [ "$YN" =~ ^(no|No|NO|n|N)$ ] ; then
echo 'Directory will not be created.'
else
echo 'Directory will be created.'
mkdir $dd
fi
fi

The output I am currently getting:
Enter the Directory:

s

$directory does not exist. Do you want to create it Y/N? $YN

Directory will be created.

I don't know what is going wrong. I have tried running it in shellcheck, but the most insight I have gained is "read without -r will mangle backslashes" & "Expressions don't expand in single quotes, use double quotes for that." What am I doing wrong.

https://redd.it/yyeyhc
@r_bash

Get the previous command output buffer

I'm working on a helper noscript that needs to run after every command to analyze its exit status and output logs.

I understand that stdout/stderr buffers are not stored on pseudo terminals. I therefore looked for a way to "save" this output to a temporary file before every command then read it after.

Here's what I added to my .bashrc:

LAST_OUTPUT_LOG_FILE="~/zero.log"
exec 3>&1 1> >(tee $LAST_OUTPUT_LOG_FILE >&3)
# based on https://superuser.com/a/1111512/1748711
echo "Using $LAST_OUTPUT_LOG_FILE"

precmd () {
    LAST_STATUS=$?
    LAST_COMMAND=$(fc -ln -1)
    echo "Last command: $LAST_COMMAND exited with status $LAST_STATUS"
    echo "--------------- LAST COMMAND LOG $LAST_OUTPUT_LOG_FILE ---------------"
    cat $LAST_OUTPUT_LOG_FILE
    echo "--------------- LAST COMMAND LOG $LAST_OUTPUT_LOG_FILE ---------------"
    # run my noscript here with the last command, its status and its output

    # reset the log file
    echo "" > $LAST_OUTPUT_LOG_FILE
}

export PROMPT_COMMAND=precmd

Except when i load a new terminal and enter a command (say ls) I get the following error:

precmd:echo:3: write error: broken pipe
precmd:3: write error: broken pipe
precmd:echo:4: write error: broken pipe
precmd:4: write error: broken pipe
cat: ~/zero.log: No such file or directory
precmd:echo:6: write error: broken pipe
precmd:6: write error: broken pipe
precmd:10: no such file or directory: ~/zero.log

Is what I'm trying to achieve possible? And if so what am I missing here?

Cheers!

https://redd.it/yyjhxo
@r_bash

If no STDIN read from File

I want a noscript which either writes STDIN to a file or if no STDIN present it reads from that file.

How could I do this? If I use cat to read STDIN, but there is no input it hangs.

Thanks

https://redd.it/yysmhu
@r_bash

so i made my own fetch using bash...
https://redd.it/yza09l
@r_bash

How to do a one liner for a CLI login which asks for a access token after login command?

I'm using beta version of a CLI as a tester which keeps asking for logging in with a access token each week when I use it. In bash terminal after I run noah login it prompts like this Enter access token > . How can I do this in a one liner like noah login > access_token?
Thanks for helping

https://redd.it/yzb4kq
@r_bash

questions about echo appending

Hello, so my problem with "echo >>" that I do not understand:

I have two files input.txt and output.txt when I loop through the lines of the first file and use "echo >>" to move them to the outputfile I have a blank first line. I understand that echo appends but then I have to question how to get rid of that? Is there no other way than deleting the first line (which seems unnecssary)?

Also if someone could explain why that behaviour is necessary instead of >> just appending beginning in the first line, that would be interesting as well.

Edit: So what my problem was, is that I did not realize that echo with no arguments does echo a blank line, so when I used it to delete the contents of a file I unwillingly inserted a blank line into it. Seems like just "> filename" is a better way to delete the contents of a file

https://redd.it/yzd9dn
@r_bash

If eval find...

I have archives of archives, at least. I would like a noscript to recursively verify all archives and sub-archives for integrity. What I have works, but I know it's dumb.

Rather than making recursion with a function that calls itself (too confusing, IDK), I've decided to just manually run find a few times. Ugh. It's still far from what I want.

declare home="${PWD}"

find . -iname '.zip' -exec sh -c '! [[ -f "${0}.val" ]] && unzip -o -d "${0%.}" "$0" && echo "$0">>$0.val' '{}' \;
find . -iname '.zip' -exec sh -c '! [[ -f "${0}.val" ]] && echo "[ERR] $0"' '{}' \;

#----------

if (
find . -iname '.zip' -exec sh -c '! [ -f "${0}.val" ] && echo "ERR $0">>"${home}log.txt"' '{}' \;
); then
echo " GOOD "
else
echo " FAIL "
fi

So, it finds zip files, and if it doesn't find "zipfile.zip.val", it extracts the contents and creates a dummy file (.val) to denote successful extraction. Then, this second part searches to make sure every .zip has an accompanying dummy file (.val).

The bottom section also just checks for the .val dummy files but instead of echo output, it just logs them and echos whether there were archives with missing .val files or not.

So, it just needs to recursively examine an archive of archives to ensure zip integrity. This is as close as I've gotten. Thanks.

OOPS: I've read that eval may be suggested over my "if (find)" sub shell method. If nothing else, maybe we can answer that!

https://redd.it/yzeqx4
@r_bash

How do I make this program exit with user input?
https://redd.it/yzeecd
@r_bash

longest||coolest Linux pipes you have written

Hello there,it's Saturday and I'm trying to cill reading about awsome pipes. Have you any cool pipe to show off?

https://redd.it/yzfh5k
@r_bash

Yet another PS1

pardon my MSYS2 setup, I don't get to decide which system I'm working on

After a metric ton of refinements, I proudly present my personal PS1 with the following features:

Colors (duh!)
Git branch + additions/deletions (Github style)
List of managed jobs
Duration and status of the last command
Left-right design
Written 100% in bash and blazing fast (okay, I may have used sed once...)
Portable (works on Windows)
Easy to configure

Here it is : https://github.com/bdelespierre/dotfiles/blob/master/bash/.bash\_ps1

I am not a bash expert, and I would love to hear your comments on that work.

Thank you for your time and have a great day!

https://redd.it/yzgxax
@r_bash

I don't understand this printf behavior

Hello everybody!
I'm new-ish to bash and found this while I was tinkering with `printf`. Let's say that I have the following noscript:

#!/usr/bin/env bash

printf -v test '%-14.*s' 14 '123456789ABCDFGH'

printf "%b\n" \
" ╭─demo─────────╮╮" \
" │ $test " \
" ╰──────────────╯"

the output comes out with 2 extra spaces added

&#x200B;

[How it comes out with just the text \\"123456789ABCDFGH\\" as the value](https://preview.redd.it/jcnkbyanv01a1.png?width=182&format=png&auto=webp&s=e3fe7ee5985e5db73fa26b0faa36ce1b15da9627)

&#x200B;

but when I set the `test` variable to `printf -v test '%-14.*s' 14 '│123456789ABCDFGH'` it comes out shifted

&#x200B;

[How it comes out with \\"│123456789ABCDFGH\\" as the value](https://preview.redd.it/b6xsteddw01a1.png?width=155&format=png&auto=webp&s=8e2cdd2479fceaf8b0096d2da1dced469f1ae681)

&#x200B;

I've also noticed this happening with nerd-font emojis (which is where I first noticed this happening), so I wonder, is there a reason why this occurs when I add the pipe "│" symbol? And if possible, can I make it always produce the second picture looking result (the shifted one), regardless of having or not the pipe?

https://redd.it/yzugcz
@r_bash

(F18) cis student need help writing an awkward command file for price calculation, professor won't help.

So I am given documents on the file I start with:

Sales for week ending November 20, 2022
"Item Price Mon Tue Wed Thu Fri Sat Sun
----------------‐----------------------------------------------------------------------------------------------------------------------
Cones 3.50 23 12 11 37 55 69 70
Ice Cream Floats 3.50 5 4 13 9 42 16 35
Sodas 2.50 10 20 13 16 22 39 25
Dipped Cones 4.50 13 14 0 22 25 35 55
Banana Splits 7.50 7 17 0 12 12 20 30
Milkshakes 5.00 16 14 15 30 37 38 41
Sundaes 6.00 11 9 12 21 20 43 34"

What I am supposed to do is write an awk command file using vim that when the command line "awk -f salesSummary.awk ProductSales.txt" is entered will output exactly this:

"Item Mon Tue Wed Thu Fri Sat Sun Total
‐----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Cones $ 80.50 $ 42.00 $ 38.50 $129.50 $192.50 $241.50 $245.00 $ 969.50
Ice Cream Floats $ 17.50 $ 14.00 $ 45.50 $ 31.50 $147.00 $ 56.00 $122.50 $ 434.00
Sodas $ 25.00 $ 50.00 $ 32.50 $ 40.00 $ 55.00 $ 97.50 $ 62.50 $ 362.50
Dipped Cones $ 58.50 $ 63.00 $ 0.00 $ 99.00 $112.50 $157.50 $247.50 $ 738.00
Banana Splits $ 52.50 $127.50 $ 0.00 $ 90.00 $ 90.00 $150.00 $225.00 $ 735.00
Milkshakes $ 80.00 $ 70.00 $ 75.00 $150.00 $185.00 $190.00 $205.00 $ 955.00
Sundaes $ 66.00 $ 54.00 $ 72.00 $126.00 $120.00 $258.00 $204.00 $ 900.00
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sales for week ending November 20, 2022
Total Sales: $5094.00
Top Seller $ 969.50 -- Cones"

What I know so far is that I structure an awk file with this syntax:

BEGIN {
-
-
-
-
}{
-
-
-
-
}
END{
-
-
}

Professor says that code is quite similar to Java but I am still lost :(
How would I go about writing this?
Ps sorry I've never used reddit before apologies for bad format.

https://redd.it/yztzir
@r_bash

Trap exit function

I have 2 questions regarding trapping exit.

1. Should the trap command come after the trap function? I assume it should, though it works with it before the trap function.
2. Why doesn't trapping exit cause a loop when the trap function exits?

Sample section of the code I've been using without any issue:

#!/usr/bin/env bash

# Trap noscript terminating errors and exit so we can clean up
trap cleanup 1 2 3 6 15 EXIT

# Tmp logs clean up function
cleanup() {
arg1=$?
# Move tmperrorlog to error log if tmperrorlog is not empty
if [ -s $Tmp_Err_Log_File ] && [ -d $Backup_Directory ]; then
mv "${TmpErrLogFile}" "${ErrLogFile}"
if [[ $? -gt "0" ]]; then
echo "WARN: Failed moving ${TmpErrLogFile} to ${ErrLogFile}" |& tee -a "${ErrLogFile}"
fi
fi
# Delete our tmp directory
if [ -d $Tmp_Dir ]; then
rm -rf "${TmpDir}"
if [[ $? -gt "0" ]]; then
echo "WARN: Failed deleting ${TmpDir}" |& tee -a "${ErrLogFile}"
fi
fi
exit "${arg1}"
}

# other code here

exit

https://redd.it/z026d9
@r_bash

"echo hello > /dev/stdout | echo world" does't make sense

Hello everyone I'm trying to understand this command behaviour, I'm remaking a shell for a school project and bash --posix behaviour looks weird to me.

Why does this command only print "world" ?
My understanding is that bash create the pipe, close it and redirect the first command STDOUT to /dev/stdout so why won't it print "hello" on the terminal ?

https://redd.it/z02289
@r_bash