shell中十种实现自加的方法

let "n = $n + 1"
: $((n = $n + 1))
((n = n+1))
n=$(($n + 1))
: $[ n = $n + 1]
n=$[ $n + 1 ]
let "n++"
(( n++ ))
: $(( n++ ))
: $[ n++ ]