.NET creates the so-called intermediate objects while building .NET projects, those are located in the “bin” and “obj” directories. The default is not very satisfying, primarily because if a program from a different machine or a container modifies those, then any cached file system paths that are encoded in the objects will be broken. But also it is probably mostly a legacy behavior to have them split between “bin” and “obj” directories.

I prefer for them to say in one - ".cache", because that’s that they are - cache. With the following configuration objects will be stored inside the ".cache" directory. Furthermore, the objects produced by the native machine in the “native” subdirectory and the ones produced by container software in “container” subdirectory.

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<PropertyGroup>
  <CachePath>.\.cache\native</CachePath>
  <CachePath Condition="'$(DOTNET_RUNNING_IN_CONTAINER)' == 'true'">.\.cache\container</CachePath>
  <MSBUildProjectExtensionsPath>$(CachePath)\obj\</MSBUildProjectExtensionsPath>
  <BaseIntermediateOutputPath>$(CachePath)\obj\</BaseIntermediateOutputPath>
  <BaseOutputPath>$(CachePath)\bin\</BaseOutputPath>
</PropertyGroup>

If anybody want to go hardcore and cache the intermediate objects based on the RID or architecture triplet, then this can also be done, for example, by adding environment variables to the path.

.NET ecosystem in Gentoo in year 2023

The Gentoo Dotnet project introduced better support for building .NET-based software using the nuget, dotnet-pkg-base and dotnet-pkg eclasses. This opened new opportunities of bringing new packages depending on .NET ecosystem to the official Gentoo ebuild repository and helping developers that use dotnet-sdk on Gentoo.

New software requiring .NET is constantly being added to the main Gentoo tree, among others that is:

• PowerShell for Linux,
• Denaro — finance application,
• Ryujinx — NS emulator,
• OpenRA — RTS engine for Command & Conquer, Red Alert and Dune2k,
• Pinta — graphics program,
• Pablodraw — Ansi, Ascii and RIPscrip art editor,
• Dafny — verification-aware programming language
• many packages aimed straight at developing .NET projects.

Dotnet project is also looking for new maintainers and users who are willing to help out here and there. Current state of .NET in Gentoo is very good but we can still do a lot better.

Special thanks to people who helped out

• Anna Figueiredo Gomes
• Esteve Varela Colominas
• Andrew Udvare

Links to bugs and announcements

• Bugs
  • gentoo-dotnet–2023/1
  • 900597
• Github PRs
  • 21112
  • 21451
  • 29309
  • 32109
  • 33940
• Active Gentoo .NET projects
  • gentoo-dotnet-guide
  • gentoo-dotnet-maintainer-tools
  • csharp-gentoodotnetinfo
  • eselect-dotnet
  • eselect-pwsh

Building PowerShell

As a part of my work of modernizing the way .NET SDK packages are distributed in Gentoo I delved into packaging a from-source build of PowerShell for Gentoo using the dotnet-pkg eclass.

Packaging pwsh was a little tricky but I got a lot of help from reading the Alpine Linux’s APKBUILD. I had to generate special C# code bindings with ResGen and repackage the PowerShell tarball. Other than this trick, restoring and building PowerShell was pretty straight forward with the NuGet package management support from the dotnet-pkg.eclass.

Alternatively if you do not want to build PowerShell you can install the binary package, I have in plans to keep that package around even after we get the non-binary app-shells/pwsh into the official Gentoo ebuild repository.

Why install modules via Portage?

But why stop on PowerShell when we can also package multiple PS modules?

Installing modules via Portage has many benefits:

• better version control,
• more control over global install,
• no need to enable PS Gallery,
• sandboxed builds,
• using system .NET runtime.

Merging the modules

PowerShell’s method of finding modules is at follows: check paths from the PSModulePath environment variable for directories containing valid .psd1 files which define the PS modules.

By default pwsh tries to find modules in paths:

• user’s modules directory — ~/.local/share/powershell/Modules
• system modules directory in /usr/local — /usr/local/share/powershell/Modules
• Modules directory inside the pwsh home — for example /usr/share/pwsh-7.3/Modules

Because we do not want to touch either /usr/local nor pwsh home, we embed a special environment variable inside the pwsh launcher script to extend the path where pwsh looks for PS modules. The new module directory is located at /usr/share/GentooPowerShell/Modules.

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dotnet-pkg-utils_append_launchervar \
    'PSModulePath="${PSModulePath}:/usr/share/GentooPowerShell/Modules:"'

So every PowerShell module will install it’s files inside /usr/share/GentooPowerShell/Modules.

To follow PS module location convention we add to that path a segment for the real module name and a segment for module version. This also enables us to have proper multi-slotting because most of the time the modules will not block installing other versions.

Take a look at this example from the app-pwsh/posh-dotnet–1.2.3 ebuild:

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src_install() {
    insinto /usr/share/GentooPowerShell/Modules/${PN}/${PV}
    doins ${PN}.psd1 ${PN}.psm1

    einstalldocs
}

And that is it. Some packages do not even need to be compiled, they just need files placed into specific location. But when compilation of C# code is needed we have dotnet-pkg to help.