Bash Gives File Details

How would I go about the following:



Create a BASH noscript called noscript3.sh which takes in a file name as a command argument.  The noscript consists of 6 logical parts. 

Part 1) Print the menu options as shown below and wait for the user response. 

1. Display the disk usage
2. Display the memory usage
3. Print the content of the specified file
4. Exit

Part 2) If option 1 is selected, execute “df -h” command. 

Part 3) If option 2 is selected, execute “free -h” command. 

Part 4) If option 3 is selected, print the content of the file as specified in the command argument.  Use “while read …  < filename” command, instead of “cat” command. 

Part 5) if option 4 is selected, end the noscript. 

Part 6) The whole noscript should be in a while true loop.

https://redd.it/ywmig6
@r_bash

Bash Directory/File Search

For an assignment, I have to make a bash noscript that takes a directory name and file name as arguments.

For the first part, it finds if the exists. If it does not exist, it prompts the user if the directory should be created. If they say they do not want to create the directory, end the noscript. Ifthe answer is yes, it creates the specified directory.

For the second part, if the specified directory already exists, it verifies that the specified file exists in the specified directory. If the file does not exist, prompt the user if the file should be created under the specified directory. If no, print the long listingof the files in the specified directory and end the noscript. If yes, create the file under the specified directory, print the long listing of the files in the specified directory, and end the noscript.

https://redd.it/ywm64c
@r_bash

Pasting a list of arguments as space-separated instead of newline-separated

I have a Python noscript which takes a variable number of arguments.

$ python handynoscript.py arg1 arg2 ... argN

The arguments come from a spreadsheet. There can be many of them.

6140839142
6147932537
6147119197
6145700817
6147950627
6147128158
6145704204
6146640673
6140994669
6147963572
6139979908
....

I currently copy the column of arguments, paste it into a text editor, do a find and replace '\n', ' 'and copy the result to paste after my noscript invocation:

$ python handynoscript.py 6140839142 6147932537 6147119197 6145700817 6147950627 6147128158 6145704204 6146640673 6140994669 6147963572 6139979908 ...

Is there a way I can do this without using the text editor steps?

https://redd.it/ywq6ge
@r_bash

Questions about piping and redirecting.

Hello, I have questions about piping and redirecting stdio.

When piping or redirecting, does stdio always follow specific rules, or are programs designed to use stdio in a specific way?

For example when I make a bash noscript, stdio does not flow into it as an argument. Why?

Same thing with other common commands, most of the time I use techniques I find online, or for some reason it just makes sense.

However, when I actually try to explore stdio with commands, I can't seem to figure out how it works. Like something ends up not working like it did in a similar example.

So I am basically asking if commands hardcode how stdio can be used with them, or does bash handle stdio the same for all commands?

https://redd.it/yx403p
@r_bash

POSIX-ly way to read two multi-line variables into columns with specified widths

I know this isn't technically Bash (POSIX sh), but I wasn't sure where to post this.

I have two multi-line variables, and I want to print them into columns where I can specify the width of each column.

LEFT="One
Two
Three
"
RIGHT="A
B
C
"

Desired output:

One A
Two B
Three C

The most "elegant" solution I was able to find unfortunately uses here strings, but was the fastest:

while read -r LEFTLINE; read -r -u 3 RIGHTLINE; do
printf "%-20b%-20b\n" "$LEFTLINE" "$RIGHTLINE"
done <<< "$LEFT" 3<<< "$RIGHT"

So I am looking for a similar way to accomplish this in POSIX sh.

I have also tried (very slow):

LEFTCOUNT=$(printf "%s" "$LEFT" | grep -c '^')
i=1
while [ "$i" -le "$LEFTCOUNT" ]; do
LEFTLINE=$(printf "%b" "$LEFT" | awk -v var="$i" 'NR==var')
RIGHTLINE=$(printf "%b" "$RIGHT" | awk -v var="$i" 'NR==var')
printf "\n%-10b%-20b" "${LEFTLINE}" "${RIGHTLINE}"
i=$(( i + 1 ))
done

And then (faster than awk, but still pretty slow):

LEFTCOUNT=$(printf "%s" "$LEFT" | grep -c '^')
i=1
while [ "$i" -le "$LEFTCOUNT" ]; do
LEFTLINE=$(printf "%s" "$LEFT" | head --lines "$i" | tail --lines "1")
RIGHTLINE=$(printf "%s" "$RIGHT" | head --lines "$i" | tail --lines "1")
printf "%-20b%-20b\n" "$LEFTLINE" "$RIGHTLINE"
i=$(( i + 1 ))
done

And finally, the simplest (however -w cannot specify individual column widths):

printf "%s\n%s\n" "$LEFT" "$RIGHT" | pr -2t

Is there a better way to do this?

https://redd.it/yx38zs
@r_bash

Bash help?

I'm very new to Bash noscripting and I need help creating the following:

Bash Menu
1. The menu items will be read from a separate text file, menu.
2. The menu must have at least 6 menu items.

https://redd.it/yx6hhv
@r_bash

How about some tags?

Posts range from those new to bash working on homework assignments, to tinkerers working on personal projects to long-timers with obscure tips or questions.

Can we get some flair/tags to help identify the context of posts?

In most situations, a poster needs a solution to a problem. Homework-related posts often require a prescribed solution with strict requirements within set boundaries. It'd be good to know in advance what sort of help is being sought, especially when new folks aren't aware how important such context is.


Potential tags:
- homework
- personal-project
- obscure
- professional-grade

Others?

Please forgive my misuse of tags vs. flair. I'm not sure what options are available to subreddit mods.

https://redd.it/yx89tp
@r_bash

Problem making an if statement to log whether a command succeeded or not

I have a function "startInstallation()" that does some clean up and directory creation then calls a java jar to the rest of the installation with the typical command "java -jar myapp.jar".

Basically I want to to make an if condition to tell wether the installation was successfull or not, if there were no errors outputted from the startInstallation function therefore it succeeded otherwise it failed.

So after googling a bit I've found the following should work:

if startInstallation ; then
log "installation was successful"
else
log "installation failed"
fi

This however always logs the "installation was successful" even if the java command fails. But why? I read this on this stackexchange post "How to conditionally do something if a command succeeded or failed" which had a lot of upvotes.

https://redd.it/yx834m
@r_bash

Converting field before delimiter to uppercase and how to replace with multiple newlines

Hi all,

I'm trying to make a little noscript that fetches all the links after a delimiter from a national news platform, cleans them up and outputs simple text and I am having trouble formatting the output

This is the noscript so far :

lynx -dump -listonly https://www.nu.nl/meest-gelezen | awk '/Hidden links/,EOF' | sed 's/.....$//' | cut -f4,6 -d'/' | tr '-' ' ' | sed 's/-/\\n/g' | tr "/" "\\n" | grep -v Hidden

Where:

\- the cut steps indicates the field I want to make uppercase, field 4 as indicated to cut, for example one line of the output at this point is:https://www.nu.nl/category-name/6236420/news-noscript

\- I'm using tr "/" "\\n" to replace one byte where I really want two as the output; two new lines would do

I think the noscript is a bit all over the place since it is probably quite possible to do all the operations with just perl or advanced regex but this approach is quite readable and quick enough, what do you think?

https://redd.it/yxboa3
@r_bash

Attempted Yes/No Directory/File Creation

I am trying to create a bash file that searches if a directory exists and, if it does not, makes it. If it does exist, it searches if the file exists and, if not, creates it. Only issue is that my bash code doesn't appear to work (due to my inexperience) and I don't know why. Help would be appreciated.

bash:

bin/bash

echo “Enter the Directory: ”

read dd

read y

if [ -d $dd \]

then

echo “$dd is valid directory and it exists. ”

if test -f “$dd”; then

echo “$dd file exists.”

else

echo “$dd file does not exist. Do you want to create it (Y/N)? ”

yes=$(echo $y | tr -s '[:upper:\]' '[:lower:\]')

if [[ "$y" = "yes" \]\] ; then

echo “File will not be created.”

else

echo “File will be created.”

touch $dd

else

echo “$directory does not exist. Do you want to create it (Y/N)? ”

yes=$(echo $y | tr -s '[:upper:\]' '[:lower:\]')

if [[ "$y" = "yes" \]\] ; then

echo “Directory will not be created.”

else

echo “Directory will be created.”

mkdir $dd

fi

&#x200B;

Output:

noscript2.sh: line 1: bin/bash: No such file or directory

&#x200B;

“Enter the Directory: ”

&#x200B;

s

&#x200B;

s

&#x200B;

sript2.sh: line 12: syntax error near unexpected token `('

&#x200B;

noscript2.sh: line 12: ` echo “$dd file does not exist. Do you want to create it (Y/N)? ”'

I have no clue where I messed up.

https://redd.it/yxk5ms
@r_bash

Checking for newly moved files in shared folder

So I have a shared folder, in which people put pdf files, which I then need to convert.
And I wanted to automate it, so I watned to do a bash noscript that will:

1. Check if there are any new pdf files in a directory
2. If there are new pdf files, execute ananother noscript ([convertert.sh](https://convertert.sh) <locationOfPDFFile>)
3. repeat

When I was testing it on local storage, I managed to do it with **inotifywait.** The problem is, inotifywait doesn't work with shared folder.

So I tried to implemet this using **find,** like this:

while $(true); do
find /mnt/pdf/ -type f -iname "*.pdf" -cmin-1
sleep 60
done;

And it works with *created* files, but when I *move* file from somewhere else to my shared fodler, the file won't show up, since technically it is not modified.
What is the best solution for this situation?

https://redd.it/yxnvac
@r_bash

Multiple Variable Solutoions

How do you go about putting multiple variables as a solution/meeting the criteria for an if/then/else statement?

Example:

The previous section of it doesn't matter that much in this instance

if test -f '$dd'; then

echo '$dd file exists.'

else

read Y/N

echo '$dd file does not exist. Do you want to create it (Y/N)? $Y/N'

read Y/N

\#How I assume you would put multiple variables

if [[ "$Y/N" = no | No | NO| n \]\] ; then

echo 'File will not be created.'

else

echo 'File will be created.'

touch $dd

fi

fi

.... To be continued

Also, can you use multiple if/then/else statements in a single bash so long as you keep them in the right columns?

https://redd.it/yxp11t
@r_bash

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.

&#x200B;

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