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Tilman
Asked: 2021-04-09 04:36:54 +0800 CST

limit output of dpkg-query -W to installed packages

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On a server running Ubuntu 20.04 LTS I am trying to list installed kernels with the command:

 dpkg-query -W -f '${Package}\n' 'linux-image-[0-9]*'

which according to the manpage should list installed packages matching the pattern. However the output of the command includes kernel versions which have already been removed. How can I limit the output to kernels which are still installed?

dpkg

1 Answers

  1. Best Answer

    The manpage on 20.04 says "all packages matching the pattern" which includes uninstalled packages. It does not claim to limit output to installed packages.

       -W, --show [package-name-pattern...]
      Just like the --list option this will list all packages matching
      the given pattern. However the output can be customized using the
      --showformat option.  The default output format gives one line per
      matching package, each line having the name (extended with the
      architecture qualifier for Multi-Arch same packages) and installed
      version of the package, separated by a tab.

    1. Add the Package state to your output

      dpkg-query -W -f '${db:Status-Status} ${Package}\n' 'linux-image-[0-9]*'

    2. Filter the output using the package state field. All values except "not-installed" mean the package is at least partly installed.

      dpkg-query -W -f '${db:Status-Status} ${Package}\n' 'linux-image-[0-9]*' | awk '$1 != "not-installed" {print}'

    3. Limit the output to the package name

      dpkg-query -W -f '${db:Status-Status} ${Package}\n' 'linux-image-[0-9]*' | awk '$1 != "not-installed" {print $2}'

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