#!/bin/bashn=1;echo -n "$n "

let "n = $n + 1" 
#note: let "n = n + 1" also worksecho -n "$n "

: $((n=$n+1)) # ":" necessary beacause otherwise bash attempts# + to interpret "$((n=$n+1))" as a commandecho -n "$n "

n=$(($n + 1 ))echo -n "$n "

: $[ n = $n + 1 ]echo -n "$n "

n=$[ $n + 1 ]echo -n "$n "echo  -e

exit 0