Question

I am trying to interweave two files that contain one sentence per line. I double spaced (sed G) the first file and I would like to incorporate the content of the second file into those empty lines.

How can I interweave both files so that the 1st line of file B goes below the 1st line in file A, the 2nd line of file B below the 2nd line of file A, until it reaches the end ?

Example: [line number|sentence number|sentence]

1  1 fileA
2   
3  2 fileA
4  
5  3 fileA
6  
7  4 fileA

Expected result:

1  1 fileA
2  1 FILEB
3  2 fileA
4  2 FILEB
5  3 fileA
6  3 FILEB
7  4 fileA

This is for a bash script: can it be done with sed or awk?

Answer 1

This might work for you (GNU sed):

sed 'R fileB' fileA

You don’t need to double space the file first.

If you want to replace the empty lines though:

sed -e '/./!{R fileB' -e ';d}' fileA