What commands produce the Free and Available results in Ubuntu System Monitor File Systems tab?

Question

Ubuntu 9.10 System Monitor (gnome-system-monitor) tab File Systems has several columns labeled: Device, Directory, Type, Total, Free, Available, Used. What command line commands would produce the Free and Available results as they show different results?

Answer 1

The command line utility that shows this data is df. It reports the total, available and used space. The “free” column in the Gnome system monitor appears to be the subtraction of the used space from the total space, which I don't think df can do for you.

The difference between available and free comes from the reserved space that exists on some filesystems. By default, 5% of each native (ext2, ext3 or ext4) filesystem is reserved to root. This is done so that the system will continue to function normally for a while even if a user fills up the disk. This is useful on OS filesystems, especially the one that contains /var, but not particularly on filesystems used for data such as /home. You can change the amount (down to 0 if you like) or the privileged user with the tune2fs command (e.g. tune2fs -r 0 /dev/mapper/foo-home to let you fill up your home volume).

Answer 2

For disk space, doesn't the command "df" list the used and available space on the hard drive partitions? Also similar is "du" which lists the usage of a folder or disk.