“dpkg -l” does not see any available package

Question

I don't understand why if I type dpkg -l mutt, I obtain no packages found matching mutt.

However mutt is there and can be installed by sudo apt-get install mutt

As far as I know dpkg (on debian) should list every package, installed or not, giving information on the package status.

Answer 1

dpkg -l will list only the packages that are installed on your machine. In your case, the package mutt is not installed. To search for packages that are installed or not, you can use aptitude search package-name-pattern.

Answer 2

Unlike aptitude or apt-cache with dpkg we can only list packages that are installed or were removed from our system.

To obtain information on a package that is or was not installed we may use

sudo apt-get update # to update the cache
apt-cache showpkg <packagename>

In case we only want to list a package that was not installed before we may issue

dpkg -l <packagename> || apt-cache showpkg <packagename>