In Debian Squeeze I have installed a packageX from debian-backports. Q1: When I apt-get dist-upgrade or aptitude full-upgrade, what release is checked for updates for packageX?  debian-backports or debian-stable?Q2: Can I use a command to update a single package from a specific release? For example is aptitude -t full-upgrade packageX a valid command? I tried aptitude -st full-upgrade packageX but the output was not helpful.Q3: For completeness purposes, what are the equivalent answers for RPM based distros?
Upgrade a single package from a target release
debian;apt;upgrade;aptitude
Q1: This depends on your current priorities. You can view the priorities with the apt-cache policy command. Here is an example of a couple of lines from the output: 500 http://security.debian.org/ stable/updates/main amd64 Packages     release v=6.0,o=Debian,a=stable,n=squeeze,l=Debian-Security,c=main     origin security.debian.org 100 http://backports.debian.org/debian-backports/ squeeze-backports/main amd64 Packages     release o=Debian Backports,a=squeeze-backports,n=squeeze-backports,l=Debian Backports,c=main     origin backports.debian.orgYou can also use apt-cache policy on a single package:$ apt-cache policy linux-image-2.6-amd64 linux-image-2.6-amd64:  Installed: (none)  Candidate: 2.6.32+29  Version table:     3.2+46~bpo60+1 0        100 http://backports.debian.org/debian-backports/ squeeze-backports/main amd64 Packages     2.6.32+29 0        500 http://apt.magazines.com/debian/ stable/main amd64 PackagesThe priorities are explained in apt_preferences(5):   P > 1000       causes a version to be installed even if this constitutes a downgrade of the package   990 < P <=1000       causes a version to be installed even if it does not come from the target release, unless the installed version is more recent   500 < P <=990       causes a version to be installed unless there is a version available belonging to the target release or the installed version is more recent   100 < P <=500       causes a version to be installed unless there is a version available belonging to some other distribution or the installed version is more recent   0 < P <=100       causes a version to be installed only if there is no installed version of the package   P < 0       prevents the version from being installedIn our example, this means that if the given package is already installed from backports, it will be upgraded from backports. If it is not installed from backports, the backports repository will not be used.Q2: The install command is used for upgrading single packages. If the package is already installed when install is given, it will be upgraded if an upgrade is available.apt-get install packageXaptitude install packageXQ3: For an RPM-based distro, it would depend on the distro. Things like yum are not tied to rpm in the same way that apt is tied to dpkg. The tool used for upgrades and remote management varies depending on distro. The yum (RHEL) and zypper (SLES) commands are the most common.