df -h 查看当前操作系统磁盘的所有盘的使用情况；
root@iZ2zec07niia7g0hr0mwufZ:/var/log# df -h
Filesystem Size Used Avail Use% Mounted on
udev 3.9G 4.0K 3.9G 1% /dev
tmpfs 799M 672K 798M 1% /run
/dev/xvda1 40G 29G 8.3G 78% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 0 5.0M 0% /run/lock
none 3.9G 4.0K 3.9G 1% /run/shm
none 100M 0 100M 0% /run/user
/dev/xvdb 50G 27G 20G 58% /data
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/c451bf365d1a3537103e23f8bbb7617119b9961fe83e193a8cff3ebfee74ebf0/merged
shm 64M 0 64M 0% /var/lib/docker/containers/b05dfb5daedb950a5a6f7ca15fd4d4ca9a3466cac675dc0208800b6f2a94c711/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/4948809a6dfccac81d84ce42dfc6befaf9cffc77ded67071fceac8f6ac8c6502/merged
shm 64M 0 64M 0% /var/lib/docker/containers/e09764e229172ec5fcae710114637e5190eb927c7e8ca7143f36bbb683063b36/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/7fe51ede018c9b402bc426ebf3eb386439da9d82eae4330476c488290f71a6b2/merged
shm 64M 0 64M 0% /var/lib/docker/containers/bb0db9510b5ad8d6adc4669dacf4d5a8a2556174e96289b2333c865612ae7f81/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/a34eb538a588eb52bc74d2cb879e7a99c2dab799f257408969366de7ffcea8d9/merged
shm 64M 0 64M 0% /var/lib/docker/containers/471ce0a8d85160ffb77571e2383ec2b879adf66a758a22facd1296ddf4d13480/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/5e710a27cc9992ce8b70a697df7115df785811d92f1aed8d0aee28e214e4fa9f/merged
shm 64M 0 64M 0% /var/lib/docker/containers/8fe2b74739a977003c6612551a1dcaa680b8926b60624d7a0118b9e6dcb2938a/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/df4424301f84da5d36ada5dbd1fae6e47ed3a780fc0b6ba666e5c2511083ad19/merged
shm 64M 0 64M 0% /var/lib/docker/containers/0e7215a04a88127cb8b249d98b53bd10862aa27c2170b8f82c00097c43abf0c2/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/09ef5690b117c231aceec9de0630ff3c304a85e54229a842e09bd537af7b1b81/merged
shm 64M 0 64M 0% /var/lib/docker/containers/d9dee1f9cf05fd8dd2ef7d29b9c2656fe01ca6870af56347545b2372d9f04789/mounts/shm
overlay 40G 29G 8.3G 78% /var/lib/docker/overlay2/06db13fb4b9555a323ae6eaa906de6bbffa34cbeecd8f751f18583ac076871ac/merged
shm 64M 0 64M 0% /var/lib/docker/containers/b18c3323c79328c2c6f7c81712b0e83bedc195964723246ace9fa51ac3d83be1/mounts/shm
du -sh * 按照文件夹统计每个文件夹下的大小
root@iZ2zec07niia7g0hr0mwufZ:/var# du -sh *
1.8M backups
472M cache
5.7G lib
4.0K local
0 lock
444M log
4.0K mail
148K megvii
4.0K opt
0 run
52K spool
4.0K tmp
du -sh 不带信息是统计当前目录下的总的大小
root@iZ2zec07niia7g0hr0mwufZ:/var# du -sh
8.6G .
