linux指令--查询磁盘空间大小

linux1:/ # df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda2             82573140  20622044  57756528  27% /
devtmpfs              16437856       168  16437688   1% /dev
tmpfs                 32875716         0  32875716   0% /dev/shm
/dev/sda6            103216920  56062184  41911524  58% /home
/dev/sda5             61931268   6036304  52749040  11% /opt
shm                   32875716         0  32875716   0% /dev/shm
linux:/ # df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              79G   20G   56G  27% /
devtmpfs               16G  168K   16G   1% /dev
tmpfs                  32G     0   32G   0% /dev/shm
/dev/sda6              99G   54G   40G  58% /home
/dev/sda5              60G  5.8G   51G  11% /opt
shm                    32G     0   32G   0% /dev/shm