8.2 How can I keep my Debian system current?
One could simply execute an anonymous ftp call to a Debian archive, then peruse
the directories until one finds the desired file, and then fetch it, and
finally install it using dpkg. Note that dpkg will
install upgrade files in place, even on a running system. Sometimes, a revised
package will require the installation of a newly revised version of another
package, in which case the installation will fail until/unless the other
package is installed.
Many people find this approach much too time-consuming, since Debian evolves so
quickly -- typically, a dozen or more new packages are uploaded every week.
This number is larger just before a new major release. To deal with this
avalanche, many people prefer to use a more automated method. Several
different packages are available for this purpose: