Rename file name in the loop

Question

I have a loop and I want to select some columns with awk and do sort, and then rename my output file with a new name. My awk and sort are working well, but I want to get a file name with a different name of my input file and I was not able to do it. I have different directories to run this loop: a, b and c. The command is:

for i in a b c 
do
    (cd $i/; for i in *_test2.txt; do awk '{print $2"_"$1}' $i | sort -V > ${i%.txt}3.txt; done)
done

I would like to change the name of the file to *_test3.txt, but in my loop I will have the output as *_test23.txt How can I do that?

Answer 1

${i%.txt} will just remove the .txt extension from the filename $i. To pick off one extra character, use ${i%?.txt}:

for i in {a,b,c}/*_test2.txt; do
  awk '{ print $2 "_" $1 }' "$i" | sort -V -o "${i%?.txt}3.txt"
done