如删除目录时先删除深路径，再删除浅路径
从少到多：/usr/bin/awk ‘{print length,$0}‘ /log/aa.txt | sort -n | sed ‘s/.* //‘ > /log/bb.txt
从多到少：/usr/bin/awk ‘{print length,$0}‘ /log/aa.txt | sort -nr | sed ‘s/.* //‘ > /log/bb.txt
shell按长度排序
原文：http://blog.51cto.com/yangzhiming/2296444
