Hi all,
I have to append every alternate line after its previous line. For example if my file has following contents
line 1: unix is an OS
line 2: it is open source
line 3: it supports shell programming
line 4: we can write shell scripts

Required output should be
line1: unix is an OS it is open source
line 2: it supports shell programming we can write shell scripts

I think this could be done using sed, but how could i do this please help?
If it cant be done using sed then please suggest other methods