@cassidoo's Interview question of the week for June 13, 2021

printArrow.sh

#!/usr/bin/env bash
set -eu -o pipefail

# Given a direction and a number of columns, write a function that outputs
# an arrow of asterisks

if [ $# -ne 2 ] || 
  ! ( ( [ $( echo $1 | tr [':upper:'] [':lower:'] ) == 'left' ] || [ $( echo $1 | tr [':upper:'] [':lower:'] ) == 'right' ] ) && [ -z "$(printf '%s\n' "$2" | sed 's/[0-9]//g')" ] ); then
  echo "$(basename $0): enter 'left' or 'right' and a positive integer, e.g. 'left 4' or 'right 3'"
  exit 1
fi

DIRECTION=$1
NUMBER=$2

function out () {
    for I in $( seq 1 $NUMBER ); do
      echo "$( printf '%*s' $(( $I-1 )) )*"
    done
}
function back () {
    for J in $( seq $(( $NUMBER-1 )) 1 ); do
      echo "$( printf '%*s' $(( $J-1 )) )*"
    done
}

case $NUMBER in
  0)
  ;;
  1)
    echo "*"
  ;;
  *)
    case $DIRECTION in
      'left')
        back; out
      ;;
      'right')
        out; back
      ;;
      *)
      ;;
    esac
  ;;
esac