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

A more-general solution (allows for more than one follow-up line to be joined) as a shell script. This adds a line between each, because I needed visibility, but that is easily remedied. This example is where the "key" line ended in : and no other lines did.

#!/bin/bash
#
# join "The rest of the story" when the first line of each   story
# matches $PATTERN
# Nice for looking for specific changes in bart output
#

PATTERN='*:';
LINEOUT=""
while read line; do
    case $line in
        $PATTERN)
                echo ""
                echo $LINEOUT
                LINEOUT="$line"
                        ;;
        "")
                LINEOUT=""
                echo ""
                ;;

        *)      LINEOUT="$LINEOUT $line"
                ;;
    esac        
done