一行脚本：统计某个字符个数

path=/abc/bdc/dsa/gafasd/casdf
计算字符'/'个数

echo -n $path | tr '/' '\n' | wc -l

echo -n $path | sed "s/[^/]//g" | wc -c

echo $[ ${#path} - `expr length ${path///}`]