[bash] why my variable is not updated? Post: 303032939

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Top Forums Shell Programming and Scripting [bash] why my variable is not updated? Post 303032939 by Don Cragun on Wednesday 27th of March 2019 04:24:18 AM

03-27-2019

Registered User

Quote:

Originally Posted by soichiro

Does anyone know why the below script is not working? Why is not the variable tot_files updated?

Code:

location=$1
cd "$location"

tot_files=0

(
    echo ""
    # recursively gets the total number of files
    tot_files=$(for t in files ; do echo `find . -type ${t:0:1} | wc -l` $t | cut -f1 -d" "; done 2> /dev/null) & 
) | wait ${!} | yad --progress --pulsate --progress-text="" --center --title="title" --text="Please wait... Reading files..." --no-buttons --no-escape --width=300 --height=200

echo "tot_files: " $tot_files

I would like to show a yad (zenity alternative) window that says to the user to wait until all the files in $1 have been counted.
That's why I used wait ${!} but I am not sure I have used in the right way.

Everything between the parentheses marked in red above is performed in a subshell. Nothing set inside that subshell will be visible in the shell that invoked that subshell (including changes to variables tot_files and !. And, since there is no wait inside the subshell, the subshell will return to the main shell before tot_files is updated in the subshell. And, the main shell has no idea that there is anything left running in the background. And, when it completes, the updated value assigned to tot_files will silently be ignored.

Furthermore, wait should never be in the middle of a pipeline; it doesn't read anything from its standard input; and even if it did, nothing from the first stage of your pipeline writes anything to its standard output.

I'm afraid I have no experience with zenity nor yad so I can only tell you what is wrong with your script; not how to fix it to make yad work.

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