Package search tools: "provided by" and "what provides"

Ubuntu community help forum has a nice page if you need to be reminded how to search files provided by a particular package.

dpkg -L will show you what files came with an installed package

apt-file, which needs to be installed first, will tell you what package provides a given file.  Actually, it can also replicate the same thing that dpkg -L does, see below:

$ dpkg -L picard-tools
/.
/usr
/usr/bin
/usr/bin/picard-tools
/usr/share
/usr/share/java
/usr/share/java/picard-1.27.jar
/usr/share/picard-tools
/usr/share/picard-tools/explain_sam_flags.py
/usr/share/doc
/usr/share/doc/picard-tools
/usr/share/doc/picard-tools/copyright
/usr/share/doc/picard-tools/README.Debian
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/picard-tools.1.gz
/usr/share/java/picard.jar

$ apt-file search picard.jar
picard-tools: /usr/share/java/picard.jar

$ apt-file list picard-tools
picard-tools: /usr/bin/picard-tools
picard-tools: /usr/share/doc/picard-tools/README.Debian
picard-tools: /usr/share/doc/picard-tools/copyright
picard-tools: /usr/share/java/picard-1.27.jar
picard-tools: /usr/share/java/picard.jar
picard-tools: /usr/share/man/man1/picard-tools.1.gz
picard-tools: /usr/share/picard-tools/explain_sam_flags.py


Addendum:  If you need to know what repository provides a specific package, use apt-cache showpkg:
$ apt-cache showpkg picard-tools
Package: picard-tools
Versions: 
1.27-1 (/var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_natty_universe_binary-amd64_Packages) (/var/lib/dpkg/status)
 Description Language: 
                 File: /var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_natty_universe_binary-amd64_Packages
                  MD5: 5ece67d6a9fa35d5b4adc3567de3557b


Reverse Depends: 
  med-bio,picard-tools
  libsam-java,picard-tools
Dependencies: 
1.27-1 - openjdk-6-jre (16 (null)) java-runtime (0 (null)) libsam-java (2 1.27-1) python (0 (null)) r-base-core (0 (null)) 
Provides: 
1.27-1 - 
Reverse Provides: