When it is necessary to know how much space is used on your disks and how much is free, the df (Disk Free) command line tool is what you need.

Usage

df [options] [filesystem-list] Options

   -a, --all
          include dummy file systems

   -B, --block-size=SIZE use SIZE-byte blocks

   -h, --human-readable
          print sizes in human readable format (e.g., 1K 234M 2G)

   -H, --si
          likewise, but use powers of 1000 not 1024

   -i, --inodes
          list inode information instead of block usage

   -k     like --block-size=1K

   -l, --local
          limit listing to local file systems

   --no-sync
          do not invoke sync before getting usage info (default)

   -P, --portability
          use the POSIX output format

   --sync invoke sync before getting usage info

   -t, --type=TYPE
          limit listing to file systems of type TYPE

   -T, --print-type
          print file system type

   -x, --exclude-type=TYPE
          limit listing to file systems not of type TYPE

   -v     (ignored)

   --help display this help and exit

   --version
          output version information and exit

Examples

If you use df with no options it will display all the available filesystems’ info

$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda1 151225248 16280980 127262392 12% / tmpfs 517924 0 517924 0% /lib/init/rw udev 10240 60 10180 1% /dev tmpfs 517924 0 517924 0% /dev/shm /dev/sdb1 76896316 54820876 18169240 76% /media/discob sshfs#ggarron@alketech.com:/home/ggarron/ 7999999992 0 7999999992 0% /mnt/remote

To better understand what is in the screen can be used the -h (human readable)

$ df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 145G 16G 122G 12% / tmpfs 506M 0 506M 0% /lib/init/rw udev 10M 60K 10M 1% /dev tmpfs 506M 0 506M 0% /dev/shm /dev/sdb1 74G 53G 18G 76% /media/discob sshfs#ggarron@alketech.com:/home/ggarron/ 7.5T 0 7.5T 0% /mnt/remote

To display only local mounted systemfilesystems use the -l (local) options, you will see the sshfs remote filesystem is not shown anymore.

$ df -hl Filesystem Size Used Avail Use% Mounted on /dev/sda1 145G 16G 122G 12% / tmpfs 506M 0 506M 0% /lib/init/rw udev 10M 60K 10M 1% /dev tmpfs 506M 0 506M 0% /dev/shm /dev/sdb1 74G 53G 18G 76% /media/discob

You can use it pointed to the device path or to the path where the filesystem is mounted

$ df -h /dev/sdb1 Filesystem Size Used Avail Use% Mounted on /dev/sdb1 74G 53G 18G 76% /media/discob

$ df -h /media/discob/ Filesystem Size Used Avail Use% Mounted on /dev/sdb1 74G 53G 18G 76% /media/discob