Question

I want a command/function, preferably bash, that takes a word/string and a number and shifts the letter positions in the word by that number, rotating the overflow back to the beginning.

e.g. with input stack and 2 the output would be cksta

I have thought about using tr but I couldn’t quite figure out how to make it general so as to work with any word, and not just translating specific letters from a target word.

Answer 1

You can use bash‘s built-in string manipulation:

#!/bin/bash

string=$1
shift=$2

length=${#string}
echo ${string:$length-$shift:$shift}${string:0:$length-$shift}

Example:

$ ./script stack 1
kstac
$ ./script stack 2
cksta
$ ./script stack 3
ackst
$ ./script stack 4
tacks