scp root@107.172.27.254:/home/test.txt . //下载文件
scp test.txt root@107.172.27.254:/home //上传文件
scp -r root@107.172.27.254:/home/test . //下载目录
scp -r test root@107.172.27.254:/home //上传目录
scp root@107.172.27.254:/home/test.txt . //下载文件
scp test.txt root@107.172.27.254:/home //上传文件
scp -r root@107.172.27.254:/home/test . //下载目录
scp -r test root@107.172.27.254:/home //上传目录