Concatenate output of two commands into one line

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)

Exactly what I needed today! Thanks! – shiri Mar 17 '17 at 14:35 — shiri, Mar 17 '17 at 14:35

score 39 · Answer 1 · answered Mar 27 '11 at 11:29

You could pass the -n option to your first echo command, so it doesn't output a newline.

As a quick demonstration, this :

echo "test : " ; echo "blah"

will get you :

test : 
blah

With a newline between the two outputs.

While this, with a -n for the first echo :

echo -n "test : " ; echo "blah"

will get you the following output :

test : blah

Without any newline between the two output.

score 20 · Accepted Answer · answered Mar 27 '11 at 11:31

20

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.

answered Mar 27 '11 at 11:31

drysdam

8,341
1
20
23

score 11 · Answer 3 · edited May 23 '17 at 12:17

11

You can use printf instead of echo, which is better for portability reasons.

edited May 23 '17 at 12:17

Community

1
1

answered Mar 27 '11 at 12:08

kurumi

25,121
5
44
52

score 9 · Answer 4 · answered Mar 27 '11 at 12:52

9

printf is the correct way to solve your problem (+1 kurumi), but for completeness, you can also do:

   echo "$file\t$qp\t$i $( ./command 2>&1 > $file-$qp-psnr.txt )" >> psnr.txt

answered Mar 27 '11 at 12:52

William Pursell

204,365
48
270
300

I guess there's no _correct_ way. drysam's solution worked for me and he was the first to answer. Thanks for this interesting one-liner though! :) – slhck Mar 27 '11 at 14:11
1

Maybe 'correct' is too strong, but printf will be more portable than echo -n. – William Pursell Mar 27 '11 at 14:41

score 0 · Answer 5 · answered Aug 27 '21 at 23:40

0

While echo -n may work if you just want the print the output to console, it won't work if you want the output redirected to file.

If you want the concatenated output to be redirected to a file, this will work:

echo "Str1: `echo "Str2"`" >> file

answered Aug 27 '21 at 23:40

sridhar krishnamurthy

51
1
1

score 0 · Answer 6 · answered Jun 07 '22 at 03:00

I was also facing the same problem. To define my problem, I have a script which is using the echo function like this:

echo -n "Some text here"
echo -n "Some text here"

The output I was getting is like this:

-n Some text here
-n Some text here

and I want the text to be in same line and it is also printing -n option in the output.

Note :- According to man Page, -n option do not print the trailing newline character.

The way I solved it using by adding the shebang in the starting of the script file like this.

#!/bin/bash
echo -n "Some text here"
echo -n "Some text here"

This will print the desired output like this:

Some text here Some text here

Hope this helps!

Concatenate output of two commands into one line

6 Answers6