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

In the case where I needed to combine two lines (for easier processing), but allow the data past the specific, I found this to be useful

data.txt

string1=x
string2=y
string3
string4

cat data.txt | nawk '$0 ~ /string1=/ { printf "%s ", $0; getline; printf "%s\n", $0; getline } { print }' > converted_data.txt

output then looks like:

converted_data.txt

string1=x string2=y
string3
string4