Question

I have a very basic shell script here:

for file in Alt_moabit Book_arrival Door_flowers Leaving_laptop
do
    for qp in 10 12 15 19 22 25 32 39 45 60
    do
        for i in 0 1
        do
            echo "$file\t$qp\t$i" >> psnr.txt
            ./command > $file-$qp-psnr.txt 2>> psnr.txt
        done
    done
done

command calculates some PSNR values and writes a detailed summary to a file for each combination of file, qp and i. That’s fine.

The 2>> outputs one line of information that I really need. But when executed, I get:

Alt_moabit  10  0
total   47,8221 50,6329 50,1031
Alt_moabit  10  1
total   47,8408 49,9973 49,8197
Alt_moabit  12  0
total   47,0665 50,1457 49,6755
Alt_moabit  12  1
total   47,1193 49,4284 49,3476

What I want, however, is this:

Alt_moabit  10  0    total  47,8221 50,6329 50,1031
Alt_moabit  10  1    total  47,8408 49,9973 49,8197
Alt_moabit  12  0    total  47,0665 50,1457 49,6755
Alt_moabit  12  1    total  47,1193 49,4284 49,3476

How can I achieve that?

(Please feel free to change the title if you think there’s a more appropriate one)

Answer 1

The (GNU version of) echo utility has a -n option to omit the trailing newline. Use that on your first echo. You’ll probably have to put some space after the first line or before the second for readability.