sed - How do I pair every two lines of a text file with Bash?

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/1513861/how-do-i-pair-every-two-lines-of-a-text-file-with-bash

Answer 1

$ sed '$!N;s/
/ /' infile
192.168.1.1 hostname1
192.168.1.2 hostname2
192.168.1.3 hostname3