假如你要在linux下删除大量文件，比如100万、1000万，像/var/spool/clientmqueue/的mail邮件， 像/usr/local/nginx/proxy_temp的nginx缓存等，那么rm -rf *可能就不好使了。

rsync提供了一些跟删除相关的参数

rsync–help | grep delete
–del an alias for –delete-during
–delete delete files that don’t exist on the sending side
–delete-before receiver deletes before transfer (default)
–delete-during receiver deletes during transfer, not before
–delete-after receiver deletes after transfer, not before
–delete-excluded also delete excluded files on the receiving side
–ignore-errors delete even if there are I/O errors
–max-delete=NUM don’t delete more than NUM files

其中–delete-before 接收者在传输之前进行删除操作

可以用来清空目录或文件，如下：

1、先建立一个空目录
mkdir /data/blank

2、用rsync删除目标目录
rsync–delete-before -d /data/blank/ /var/spool/clientmqueue/

这样目标目录很快就被清空了

又假如你有一些特别大的文件要删除，比如nohup.out这样的实时更新的文件，动辄都是几十个G上百G的，也以用rsync来清空大文件，而且效率比较高

1、创建空文件
touch /data/blank.txt

2、用rsync清空文件
rsync-a –delete-before –progress –stats /root/blank.txt /root/nohup.out

building file list …
1 file to consider
blank.txt
0 100% 0.00kB/s 0:00:00 (xfer#1, to-check=0/1)

Number of files: 1
Number of files transferred: 1
Total file size: 0 bytes
Total transferred file size: 0 bytes
Literal data: 0 bytes
Matched data: 0 bytes
File list size: 27
File list generation time: 0.006 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 73
Total bytes received: 31

sent 73 bytes received 31 bytes 208.00 bytes/sec
total size is 0 speedup is 0.00

tips：
当SRC和DEST文件性质不一致时将会报错
当SRC和DEST性质都为文件【f】时，意思是清空文件内容而不是删除文件
当SRC和DEST性质都为目录【d】时，意思是删除该目录下的所有文件，使其变为空目录
最重要的是，它的处理速度相当快，处理几个G的文件也就是秒级的事
最核心的内容是：rsync实际上用的就是替换原理

转载来自：http://www.tuicool.com/articles/6Nvqem