$ aptitude show with no arguments should print a usage message.
Hi Dan, Dan Jacobson wrote: Indeed. Or at least do something useful instead of just loading the whole DB and then exiting. Thanks for the report! Regards, Axel
To be picky, one also notices the man page says <packages>,
which means they are required:
aptitude [<options>...] {build-dep | build-depends | changelog |
download | forbid-version | hold | install | markauto | purge
| reinstall | remove | show | showsrc | source | unhold |
unmarkauto | versions} <packages>...
But for e.g., install, purge, that isn't actually the case.