shirish@Mugglewille:~$ aptitude search matroska
p libmatroska-dev - extensible open standard audio/video container format
i A libmatroska0 - extensible open standard audio/video container format
p libmatroska0-dbgsym - debug symbols for package libmatroska0
libmatroska is installed.
shirish@ Mugglewille: ~$ aptitude search matroska
p libmatroska-dev - extensible open standard audio/video container format
i A libmatroska0 - extensible open standard audio/video container format
p libmatroska0-dbgsym - debug symbols for package libmatroska0