Usefull Linux commands not to forget
Backup with TAR
You can unarchieve as,
tar -xvjf <filesystem>.tar.bz2
Or use gunzip with tar as,
tar -cvzf and tar -xvzf
-p Restore the named files to their original modes, and ACLs if applicable, ignoring the present umask(1) . This is the default behavior if invoked as super-user with the x function letter specified. If super-user, SETUID and sticky information are also extracted, and files are restored with their original owners and permissions, rather than owned by root. When this function modifier is used with the c function, ACLs are created in the tarfile along with other information. Errors will occur when a tarfile with ACLs is extracted by previous versions of tar .
tar -czvfp /hd1.tar * --exclude-from backup-x
Backup Entrie System
If you want to backup an entire system, I wond use another disk ass mirror and would type
dd if=<disk_device> bs=1024 of=<your_mirror_disk_device>