Welcome to LQ!
For information on slackpkg, type 'man slackpkg' at the command line, or see
http://docs.slackware.com/slackware:slackpkg
The 'slackpkg upgrade-all' command generates a list of packages available for upgrade. You select which packages you wish to upgrade. With default configuration, the packages are then downloaded and installed. You may see additional prompts if further action is required, e.g. updating configuration files. The action that slackpkg is conducting is generally very obvious from the screen messages.
