Linux var
From wikinotes
/var
Data that is changed while the system is running.
/var/games
variable data belonging to games is placed here in case /usr is mounted as read only.
/var/lock
Lock files are created by programs while they are using a device. When other programs see that the device is locked, they will stop trying to use the device.
/var/log
/var/log/wtmp login logs /var/log/messages syslog logs log files may grow indefinitely, you should clean this out periodically.
/var/mail /var/spool/mail
User mailbox files
/var/run
contains info about the system that is valid until next boot. ex: /var/run/utmp shows all users logged in
/var/spool
News, printer queues, Mail, other queued work.
/var/tmp
Temporary files that are either large, or need to exist longer than is allowed for /tmp.
