How can I write in nth column of a file in awk?

Question

For example:

abc
xyz
123
546

input.txt:

asdad
asdad
adghf
dfytr

I wanted to add the above column in 2nd c

Answer 1

The command you're looking for is paste rather than awk. You could do it in awk but you'll probably find that paste is easier:

pax> cat qq1
asdad
asdad
adghf
dfytr

pax> cat qq2
abc
xyz
123
546

pax> paste qq1 qq2
asdad   abc
asdad   xyz
adghf   123
dfytr   546

Use paste -d' ' qq1 qq2 if you want a space rather than a tab for the delimiter.