# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/^(.*?)\.((?:\.?[0-9]+){3,}(?:[-a-z]+)?)\.nupkg$/Package: \1 Version: \2/gm;t' <<< "knockoutjs.3.4.2.nupkg
log4net.2.0.8.nupkg
runtime.tizen.4.0.0-armel.microsoft.netcore.jit.2.0.0.nupkg
nuget.core.2.7.0-alpha.nupkg
microsoft.identitymodel.6.1.7600.16394.nupkg
Package: knockoutjs Version: 3.4.2
Package: log4net Version: 2.0.8
Package: runtime.tizen.4.0.0-armel.microsoft.netcore.jit Version: 2.0.0
Package: nuget.core Version: 2.7.0-alpha
Package: microsoft.identitymodel Version: 6.1.7600.16394
"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html