Which directory should I backup for a full backup?

Some directories are created or not necessary for a full backup, e.g., /mnt or /proc or /tmp Which other directories can I omit for a full backup? -- Ronald Wiplinger (CEO of ELMIT) http://www.elmit.com +886 (0) 915 653-452 - I'm a SpamCon Foundation Member, #694, Verify it at http://www.spamcon.org