How to print columns one after the other in bash?

Question

Is there any better methods to print two or more columns into one column, for example

input.file

AAA    111
BBB    222
CCC    333

o

Answer 1

Ugly, but it works-

for i in {1..2} ; do awk -v p="$i" '{print $p}' input.file ; done

Change the {1..2} to {1..n} where 'n' is the number of columns in the input file

Explanation-

We're defining a variable p which itself is the variable i. i varies from 1 to n and at each step we print the 'i'th column of the file.