This command lists all packages that have upgrades available within the current preferred_state or the installed package's stability, whichever is less stable. This command does not list releases that are incompatible with the current PHP version.
If package X is installed with version 0.3.0, stability alpha, and preferred_state is stable, Pyrus will list the newest version available that satisfies stability of alpha, beta or stable. If package Y is also installed, with version 1.2.3, stability stable, only the latest stable release will be listed. In both cases, if the latest available version that satisfies these requirements is not found, none will be listed.
Another example: If package X is installed with version 1.0.0, stability stable, and the preferred_state is alpha, Pyrus will list the newest version available that satisfies stability of alpha, beta or stable.