While Linux has a number of very nice GUIs, using the command-line interface can be faster and produce more information than GUI tools can, especially when it comes to reporting and viewing disk usage.

The df tool simply reports the amount of free space on each partition — how large they are, etc. It also provides information on non-local filesystems (such as mounted NFS or Samba shares). In its most basic form, df provides the following:

$ df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/md2               4881472    793508   4087964  17% /

However, you can add options to df to show the filesystem type and show the sizes in an easier to understand format:

$ df -h -T
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/md2       xfs    4.7G  775M  3.9G  17% /

df can also list remotely mounted filesystems:

df -hT 
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/md2       xfs    4.7G  786M  3.9G  17% /
/dev/md0      ext2    145M  7.2M  130M   6% /boot
atlas:/mnt/BIG nfs    465G  306G  160G  66% /.automount/atlas/root/mnt/BIG
             smbfs    254G  140G  115G  55% /mnt/Files

This shows the NFS mount /mnt/BIG from the system atlas is automounted, and shows that the Samba share Files from the system surtr is mounted as well.

While df provides an overview of entire partitions, the du tool will summarize the size of a given directory, broken down by subdirectories:

$ du svn/ports
32      svn/ports/vnstat/.svn
48      svn/ports/vnstat
6248    svn/ports

Of course, to summarize the directory and all subdirectories and display size values in a human-readable format, use:

$ du -sh svn/ports
6.2M    svn/ports

Finally, to get a list of all the mounted filesystems on the system, use the mount command. It will not only show the mounted filesystems, but the associated mount options with each and those special filesystems that df does not show:

# mount
/dev/md2 on / type xfs (rw)
none on /proc type proc (rw)
none on /proc/bus/usb type usbfs (rw)
none on /sys type sysfs (rw)
/dev/md0 on /boot type ext2 (rw,nosuid,nodev,noatime)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
build:(pid2286,port1022) on /net type nfs (intr,rw,port=1022,toplvl,map=/etc/amd.net,noac)
atlas:/mnt/BIG on /.automount/atlas/root/mnt/BIG type nfs (nosuid,nodev,rsize=32768,wsize=32768,intr,noatime,vers=3,proto=tcp)
//surtr/Files on /mnt/Files type smbfs (0)

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