du alternative

1.sh

#!/bin/bash

my_du () {
    ans=0
    for file in $(find $1)
    do
        if [ -f $file ]
        then
            sz=$(wc -c $file | { read first rest; echo $first; })
            ans=$(expr $ans + $sz)
        fi
    done
    echo $ans
    return 0;
}

my_du $1