In 'apt-cache depends' output, what is the meaning of Suggests, Recommends, |, <>?

Solution 1:

The authoritative reference is the Debian policy manual: http://www.debian.org/doc/debian-policy/

Quoting the manual:

The Recommends field should list packages that would be found together with this one in all but unusual installations.

Suggests: This is used to declare that one package may be more useful with one or more others. Using this field tells the packaging system and the user that the listed packages are related to this one and can perhaps enhance its usefulness, but that installing this one without them is perfectly reasonable.

These days packages that are recommended are installed as well by default ( when you install the package doing the recommending ).

As you guessed the | indicates "or". The control line normally shows foo | bar, but apt-cache depends appears to reformat it by showing each alternative on its own line and prefixing the first with the |. In other words, the pipe flags the preferred option and the next line is the alternative.

The package listed in angle brackets indicates that it is a virtual package. The packages listed on the indented lines after it are the various packages that provide that service.