Like the title.
reinstall the ubuntu and cp all the file(same pc,same ubuntu version" to the "new ubuntu" root("\".
the "new ubuntu" can boot or not?
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my means I want partition the hda and mv all the now setting and applications to the new partition.

Thank you very much

You should use df. My memory isn't working right now so you'd need to read the man page. Also, there's a good tutorial somewhere on LQ.

not so easy, after u move all, u won't able to boot. The general step-by-step as below:
1. partition ur hdd
2. Check new partition table, sometimes you need to reboot your PC. Probably you won't able to boot so prepare live cd as backup.
3. mount new partition some where else. then copy all files there, if I'm not mistaken you no need to copy /proc, /dev.
4. Edit the fstab file at /newpartition/etc/fstab
5. Reinstall the grub, i think this will be tricky cause you don't make /boot as a dedicated partition (~100M) which is strongly recommended.

Somebody please give comment if I miss up something.
Regards,
Ks