Contains variable data like system logging files, mail and
printer spool directories, and transient and temporary files.
Some portions of /var are not shareable between different
systems. For instance, /var/log, /var/lock, and /var/run. Other
portions may be shared, notably /var/mail, /var/cache/man,
/var/cache/fonts, and /var/spool/news. Why not put it into /usr?
Because there might be circumstances when you may want to mount
/usr as read-only, e.g. if it is on a CD or on another computer.
'/var' contains variable data, i.e. files and directories the
system must be able to write to during operation, whereas /usr
should only contain static data. Some directories can be put
onto separate partitions or systems, e.g. for easier backups,
due to network topology or security concerns. Other directories
have to be on the root partition, because they are vital for the
boot process. 'Mountable' directories are: '/home', '/mnt',
'/tmp', '/usr' and '/var'. Essential for booting are: '/bin',
'/boot', '/dev', '/etc', '/li