How to use df

The df command is used to view the amount of free diskspace on a server.  The most common usage of this command will include the -h flag.  This flag will make the output be more human readable.

Here is an example of this command:
# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda7            1012M  573M  388M  60% /
/dev/sda1              99M   31M   64M  33% /boot
none                  2.0G     0  2.0G   0% /dev/shm
/dev/sda8              51G   37G   13G  75% /home
/dev/sda6            1012M   35M  926M   4% /tmp
/dev/sda2             6.6G  4.4G  1.9G  71% /usr
/dev/sda5             6.0G  2.1G  3.7G  37% /var
/dev/sdb1              68G   35G   30G  54% /home2
/tmp                 1012M   35M  926M   4% /var/tmp

This command provides some useful information about current free space on your system.  This would be a good thing to check before adding any new large clients to a server.  Checking the free disk space can assure that you have sufficient space for the new account.