I've tried to install Pantheon desktop environment several times. I tried sudo apt-get update and sudo apt-get upgrade, but it's no use. I’m just a very new beginner. This is what I’ve done:
quanglong@ubuntu:~$ sudo add-apt-repository ppa:elementary-os/daily[sudo] password for quanglong: You are about to add the following PPA to your system: ATTENTION!Do NOT install this PPA if you want a tested running system, this PPA contains the newest and most unstable development of elementary, it's useful only if you are a developer and are not afraid to encounter CRITICAL BUGS.Also this PPA may overwrite already installed packages you don't want it to! More info: https://launchpad.net/~elementary-os/+archive/dailyPress [ENTER] to continue or ctrl-c to cancel adding itgpg: keyring `/tmp/tmpkz5d_z/secring.gpg' createdgpg: keyring `/tmp/tmpkz5d_z/pubring.gpg' createdgpg: requesting key 4E1F8A59 from hkp server keyserver.ubuntu.comgpg: /tmp/tmpkz5d_z/trustdb.gpg: trustdb createdgpg: key 4E1F8A59: public key "Launchpad PPA for elementary OS team" importedgpg: Total number processed: 1gpg: imported: 1 (RSA: 1)OK/bin/rm: cannot remove `/run/user/root/gvfs': Is a directoryquanglong@ubuntu:~$ sudo apt-get updateHit http://ppa.launchpad.net quantal Release.gpg Get:1 http://security.ubuntu.com quantal-security Release.gpg [933 B] Hit http://us.archive.ubuntu.com quantal Release.gpg Hit http://ppa.launchpad.net quantal Release.gpgGet:2 http://security.ubuntu.com quantal-security Release [49.6 kB]Get:3 http://us.archive.ubuntu.com quantal-updates Release.gpg [933 B] Hit http://us.archive.ubuntu.com quantal-backports Release.gpg Hit http://ppa.launchpad.net quantal Release Hit http://us.archive.ubuntu.com quantal Release Hit http://ppa.launchpad.net quantal Release Get:4 http://us.archive.ubuntu.com quantal-updates Release [49.6 kB] Hit http://ppa.launchpad.net quantal/main Sources Get:5 http://security.ubuntu.com quantal-security/main Sources [74.3 kB] Hit http://ppa.launchpad.net quantal/main amd64 Packages Hit http://ppa.launchpad.net quantal/main i386 Packages Hit http://us.archive.ubuntu.com quantal-backports Release Hit http://us.archive.ubuntu.com quantal/main Sources Hit http://us.archive.ubuntu.com quantal/restricted Sources Hit http://us.archive.ubuntu.com quantal/universe SourcesHit http://ppa.launchpad.net quantal/main Sources Hit http://us.archive.ubuntu.com quantal/multiverse Sources Get:6 http://security.ubuntu.com quantal-security/restricted Sources [1,833 B]Hit http://us.archive.ubuntu.com quantal/main amd64 Packages Hit http://ppa.launchpad.net quantal/main amd64 Packages Hit http://us.archive.ubuntu.com quantal/restricted amd64 PackagesGet:7 http://security.ubuntu.com quantal-security/universe Sources [23.8 kB]Hit http://ppa.launchpad.net quantal/main i386 Packages Hit http://us.archive.ubuntu.com quantal/universe amd64 Packages Hit http://us.archive.ubuntu.com quantal/multiverse amd64 Packages Get:8 http://security.ubuntu.com quantal-security/multiverse Sources [1,169 B]Hit http://us.archive.ubuntu.com quantal/main i386 Packages Hit http://us.archive.ubuntu.com quantal/restricted i386 Packages Get:9 http://security.ubuntu.com quantal-security/main amd64 Packages [207 kB]Hit http://us.archive.ubuntu.com quantal/universe i386 Packages Hit http://us.archive.ubuntu.com quantal/multiverse i386 Packages Hit http://us.archive.ubuntu.com quantal/main Translation-en Hit http://us.archive.ubuntu.com quantal/multiverse Translation-en Hit http://us.archive.ubuntu.com quantal/restricted Translation-en Hit http://us.archive.ubuntu.com quantal/universe Translation-en Get:10 http://us.archive.ubuntu.com quantal-updates/main Sources [134 kB] Get:11 http://security.ubuntu.com quantal-security/restricted amd64 Packages [3,469 B]Get:12 http://security.ubuntu.com quantal-security/universe amd64 Packages [72.4 kB]Ign http://ppa.launchpad.net quantal/main Translation-en_US Get:13 http://us.archive.ubuntu.com quantal-updates/restricted Sources [2,564 B]Ign http://ppa.launchpad.net quantal/main Translation-en Get:14 http://us.archive.ubuntu.com quantal-updates/universe Sources [96.7 kB] Ign http://ppa.launchpad.net quantal/main Translation-en_US Get:15 http://security.ubuntu.com quantal-security/multiverse amd64 Packages [1,488 B]Ign http://ppa.launchpad.net quantal/main Translation-en Get:16 http://security.ubuntu.com quantal-security/main i386 Packages [205 kB] Get:17 http://us.archive.ubuntu.com quantal-updates/multiverse Sources [5,269 B]Get:18 http://us.archive.ubuntu.com quantal-updates/main amd64 Packages [337 kB]Get:19 http://us.archive.ubuntu.com quantal-updates/restricted amd64 Packages [4,804 B]Get:20 http://us.archive.ubuntu.com quantal-updates/universe amd64 Packages [218 kB]Get:21 http://security.ubuntu.com quantal-security/restricted i386 Packages [3,531 B]Get:22 http://security.ubuntu.com quantal-security/universe i386 Packages [73.0 kB]Get:23 http://us.archive.ubuntu.com quantal-updates/multiverse amd64 Packages [12.1 kB]Get:24 http://security.ubuntu.com quantal-security/multiverse i386 Packages [1,726 B]Hit http://security.ubuntu.com quantal-security/main Translation-en Get:25 http://us.archive.ubuntu.com quantal-updates/main i386 Packages [334 kB]Hit http://security.ubuntu.com quantal-security/multiverse Translation-en Hit http://security.ubuntu.com quantal-security/restricted Translation-en Hit http://security.ubuntu.com quantal-security/universe Translation-en Get:26 http://us.archive.ubuntu.com quantal-updates/restricted i386 Packages [4,841 B]Get:27 http://us.archive.ubuntu.com quantal-updates/universe i386 Packages [219 kB]Get:28 http://us.archive.ubuntu.com quantal-updates/multiverse i386 Packages [12.3 kB]Hit http://us.archive.ubuntu.com quantal-updates/main Translation-en Hit http://us.archive.ubuntu.com quantal-updates/multiverse Translation-en Hit http://us.archive.ubuntu.com quantal-updates/restricted Translation-en Hit http://us.archive.ubuntu.com quantal-updates/universe Translation-en Hit http://us.archive.ubuntu.com quantal-backports/main Sources Hit http://us.archive.ubuntu.com quantal-backports/restricted Sources Ign http://security.ubuntu.com quantal-security/main Translation-en_US Hit http://us.archive.ubuntu.com quantal-backports/universe Sources Ign http://security.ubuntu.com quantal-security/multiverse Translation-en_US Hit http://us.archive.ubuntu.com quantal-backports/multiverse Sources Ign http://security.ubuntu.com quantal-security/restricted Translation-en_US Hit http://us.archive.ubuntu.com quantal-backports/main amd64 Packages Ign http://security.ubuntu.com quantal-security/universe Translation-en_US Hit http://us.archive.ubuntu.com quantal-backports/restricted amd64 Packages Hit http://us.archive.ubuntu.com quantal-backports/universe amd64 Packages Hit http://us.archive.ubuntu.com quantal-backports/multiverse amd64 Packages Hit http://us.archive.ubuntu.com quantal-backports/main i386 Packages Hit http://us.archive.ubuntu.com quantal-backports/restricted i386 Packages Hit http://us.archive.ubuntu.com quantal-backports/universe i386 Packages Hit http://us.archive.ubuntu.com quantal-backports/multiverse i386 Packages Hit http://us.archive.ubuntu.com quantal-backports/main Translation-en Hit http://us.archive.ubuntu.com quantal-backports/multiverse Translation-en Hit http://us.archive.ubuntu.com quantal-backports/restricted Translation-en Hit http://us.archive.ubuntu.com quantal-backports/universe Translation-en Ign http://us.archive.ubuntu.com quantal/main Translation-en_US Ign http://us.archive.ubuntu.com quantal/multiverse Translation-en_USIgn http://us.archive.ubuntu.com quantal/restricted Translation-en_USIgn http://us.archive.ubuntu.com quantal/universe Translation-en_USIgn http://us.archive.ubuntu.com quantal-updates/main Translation-en_USIgn http://us.archive.ubuntu.com quantal-updates/multiverse Translation-en_USIgn http://us.archive.ubuntu.com quantal-updates/restricted Translation-en_USIgn http://us.archive.ubuntu.com quantal-updates/universe Translation-en_USIgn http://us.archive.ubuntu.com quantal-backports/main Translation-en_USIgn http://us.archive.ubuntu.com quantal-backports/multiverse Translation-en_USIgn http://us.archive.ubuntu.com quantal-backports/restricted Translation-en_USIgn http://us.archive.ubuntu.com quantal-backports/universe Translation-en_USFetched 2,151 kB in 45s (47.7 kB/s)Reading package lists... Done/bin/rm: cannot remove `/run/user/root/gvfs': Is a directoryquanglong@ubuntu:~$ sudo apt-get install elementary-desktopReading package lists... DoneBuilding dependency tree Reading state information... DoneE: Unable to locate package elementary-desktop/bin/rm: cannot remove `/run/user/root/gvfs': Is a directoryquanglong@ubuntu:~$