For all files in folder with string in name, add value in cell (2,9) to the end of file name

Question

Ok, I have many files in a folder that have the string "$varname.txt"` in their name:

for file in find output/ -name "*$varname*.txt" -type f; do echo $file; done

...

now these files all have two lines and 9 columns to them. I want to add the content of line 2, col 9 to the end of their filname (right before the .txt).

So I know how to print the value of in cell(2, 9) of all these files:

find output/ -name "*$varname*.txt" -type f -exec awk -F' ' 'NR==2{print $9}' {} \;

What I struggle with is how to put that string as the last thing before the extension in those filenames

Answer 1

You need to capture the value and construct the new filename with it.

find output/ -name "*$varname*.txt" -type f -exec sh -c '
    for file; do
        value=$(awk "NR==2 {print \$9; exit}" "$file")
        echo mv "$file" "${file%.*}$value.${file##*.}"
    done
' sh {} +

I'm calling a shell script in the -exec directive, passing several filenames to it (with -exec ... + instead of -exec ... \;)

The trailing "sh" becomes $0, and the filenames go into $1, $2, etc

Answer 2

Here’s a GNU parallel approach:

find output/ -name "*$varname*.txt" -type f -print0 |
parallel -0 'echo mv {} {.}$(awk -F" " "NR==2{print\$9}" {}).{=s/.*\.//=}'

This pipes the zero-delimited file list to parallel which lists the renaming commands – remove echo if it does the right thing. parallel comes with handy replacement strings, {} is replaced by the (currently processed) input file name, {.} by the input filename without extension and with {=perl expression=} you can run anything perl can do, like a substitution here. The output of your awk command is simply added using Command Substitution.