Rearrange columns using cut

Question

I am having a file in the following format

Column1    Column2
str1       1
str2       2
str3       3

I want the columns to be rearranged. I tried below

Answer 1

You may also combine cut and paste:

paste <(cut -f2 file.txt) <(cut -f1 file.txt)

via comments: It's possible to avoid bashisms and remove one instance of cut by doing:

paste file.txt file.txt | cut -f2,3