Change Filename in Pipe

Question

I have a for loop that accepts a file with one type of extension, but the final command in the pipe requires the STDIN file to have an extension of another type. In my pipe I use awk to change the file type so that it is properly formatted for the final command, but the extension is still linked to the initial input file.

For example:

for file in *.AAA
do
commandA $file | awk ' { print } ' | commandB

A typical use of commandB:

commandB -i myfile.BBB

Is there a way for me to change the extension of a file in the middle of a for loop & pipe?

Answer 1

I think you can change the extension of a file in the middle of a for loop and pipe, As you see ${file%.*} is a cool trick that basically removes the file extension (*.AAA) from the original file name, and then, I add the .BBB extension to create the new file name, which I call new_file,and to top it off,I pass this modified file to commandB with the -i option!

for file in *.AAA
do
    new_file="${file%.*}.BBB"  #change the extension to .BBB
    commandA "$file" | awk '{ print }' | commandB -i "$new_file"

or you can use process substitution, so I use sed to change the file extension from .AAA to .BBB in the file name,and then, I pass this fancy modified file name to commandB using something called process substitution, which treats the command's output like a temporary file :

for file in *.AAA; do
    commandA "$file" | awk '{ print }' | commandB -i <(commandA "$file" | awk '{ print }' | sed 's/\.AAA$/.BBB/')
done