How to pipe grep output to paste input?

Question

I basically want to take the line that is under the word "LOAD" in filename1, and make it the second column in a new file, where the first column comes from filename2. (This is being done inside a loop, but I think that's irrelevant.)

So if I have

grep -A 1 LOAD filename1 >> temp
paste filename2 temp >> filename3
rm temp

Is there a way to do that in one command, with no temp file? Something like

grep -A 1 LOAD filename1 | paste filename2 "grep output" >> filename3

Answer 1

You can use process substitution instead of using a temporary file:

paste filename2 <(grep -A 1 LOAD filename1) >> filename3

Answer 2

You can use '-' to represent the input from the pipe

grep -A 1 LOAD filename1.txt | paste filename2.txt - >> filename3.txt

Answer 3

grep -A 1 LOAD filename1.txt  | paste filename2.txt /dev/stdin >> filename3.txt