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My old computer, with Ubuntu 10.04, crashed, and I installed Ubuntu 12.04 on a new computer. Luckily, I have a full backup of my previous file system. However, I don't know what folders exactly I need to restore (except the home folder, of course), since restoring the wrong files might damage the new files that came with the fresh installation.

I suppose that if I understand what each folder is used for, I can know whether it makes sense to restore it. Specifically, I would like to know about the following folders:

  • /boot - What is it? Should I restore it? (my 12.04 computer currently boots OK).
  • /etc - contains a lot of folders, most of them also exist on my 12.04 computer. Should I just restore all the /etc folder? Should I do it before or after I install the relevant applications?
  • /etc/apache2 - I changed some configurations. However, the I already installed apache2 on my 12.04 computer, and the configuration files look different. Probably the new version of apache2 has some new configurations. Should I just merge each file manually? same question with /etc/mysql.
  • /var/backups - Contains some files I don't recognize, such as aptitude.pkgstates., dpkg.status., group.bak, shadow.bak, etc. Most of them already exist on my new /var/backup . Who creates those files, and who users them? Do I need to restore them?
  • /var/cache - many folders that I don't recognize. Who created them? Who uses them? Should I restore them?
  • /var/lib - again, many folders that I don't recognize. Specifically:
  • /var/lib/mysql - contains my old databases. Is it safe to just copy all of them? Should I do this before or after I re-install MySQL? Are they compatible with the new version? (I had 5.1, the current version is 5.5)
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up vote 4 down vote accepted
  1. /boot: Initial boot (kernel/initramfs) images and other boot configuration. DO NOT restore.
  2. /etc: Usually all kinds of configuration files for the system and other applications. DO NOT restore except for single configuration files for specific applications.
  3. /etc/apache2 and /etc/mysql: reinstall and intelligently merge/copy old configuration over to new config files.
  4. /var/backups: most are dynamically created and managed by the system. DO NOT restore.
  5. /var/cache: same as above, DO NOT restore.
  6. /var/lib, /var/lib/mysql, /var/www, etc.: restore only the DATA (or import it, etc.) after reinstalling the applications (apache, mysql, etc.).
share|improve this answer
Great summary, thanks. – Erel Segal-Halevi Jul 30 '12 at 4:52

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