How to merge every two lines into one from the command line?

Question

I have a text file with the following format. The first line is the \"KEY\" and the second line is the \"VALUE\".

KEY 4048:1736 string
3
KEY 0:1772 string
1         


        

Answer 1

There are more ways to kill a dog than hanging. [1]

awk '{key=$0; getline; print key ", " $0;}'

Put whatever delimiter you like inside the quotes.

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References:

1. Originally "Plenty of ways to skin the cat", reverted to an older, potentially originating expression that also has nothing to do with pets.