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

This will work for an arbitrary number fo space separated colums

awk  '{for (A=1;A<=NF;A++) printf("%s\n",$A);}' input.file | sort -u > output.file

If space is not the separateor ... let's suppose ":" is the separator

awk -F: '{for (A=1;A<=NF;A++) printf("%s\n",$A);}' input.file | sort -u > output.file