sharex/build-linux-binary

You are an expert Linux build automation specialist for .NET/Avalonia projects.

Follow these instructions exactly and in order to build Linux binaries for XerahS.

<task> <goal>Build Linux packages (deb/rpm) for both x64 and ARM64 architectures.</goal> <goal>Handle file locking issues that occur when a previous build is still running.</goal> <goal>Avoid Avalonia XAML precompilation failures caused by namespace mismatches in converters.</goal> <goal>Validate that the build artifacts exist and are recent.</goal> </task> <context> <build_script_path>build/linux/package-linux.sh</build_script_path> <dist_output_path>dist/</dist_output_path> <expected_outputs> - XerahS-{version}-linux-x64.deb - XerahS-{version}-linux-arm64.deb - XerahS-{version}-linux-x64.rpm (if rpmbuild is available) - XerahS-{version}-linux-arm64.rpm (if rpmbuild is available) </expected_outputs> </context>

Shared Build Guardrails

Before Linux packaging work, follow build-common for shared timeout, lock recovery, no-concurrent-build, -m:1, TFM, and SkiaSharp rules. This Linux skill owns package-linux usage, log monitoring, Linux artifact validation, and Linux-specific XAML precompilation diagnostics.

Build Process

Phase 0: Update ShareX.ImageEditor Submodule

Always pull the latest ShareX.ImageEditor submodule before building to ensure the embedded image editor is up-to-date.

git submodule update --remote --merge ShareX.ImageEditor

Phase 1: Pre-Build Cleanup

CRITICAL: Stale dotnet and package-linux.sh processes are the #1 cause of file lock failures on Linux. Always kill them before starting.

1. Kill all stale build processes:

   pkill -f "package-linux.sh" 2>/dev/null
   pkill -f "dotnet publish" 2>/dev/null
   pkill -f "dotnet build" 2>/dev/null
   sleep 2
   

2. Optional — clean obj folders if locks persist:

   rm -rf /path/to/XerahS/ShareX.ImageEditor/src/ShareX.ImageEditor/obj/Release
   

   This is most useful if you see The process cannot access the file '...ShareX.ImageEditor.pdb' because it is being used by another process (Avalonia AVLN9999 error).

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Phase 2: Run the Build Script

IMPORTANT: Always redirect output to a log file. The build takes 5-15 minutes and command_status produces no output during that time — the tool will appear to hang. Do NOT use WaitDurationSeconds > 30 with this command.

Start the build with log redirection:

bash build/linux/package-linux.sh > build_output.log 2>&1

This runs in the background. Monitor progress by periodically reading the log with view_file:

view_file: /path/to/XerahS/build_output.log  (last 50 lines)

Repeat every ~30 seconds until you see one of:

• Done! All packages in dist/ → ✅ Build succeeded
• Error: or FAILED lines → ❌ See Phase 3 for fixes

Do NOT use WaitDurationSeconds=120 in command_status — the command produces buffered output only after completion, so polling the log file is the only reliable way to track progress.

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Phase 3: Handle Common Failures

🔴 Failure: No precompiled XAML found for XerahS.UI.App

Symptom (at runtime, not build time):

Avalonia.Markup.Xaml.XamlLoadException: No precompiled XAML found for XerahS.UI.App, 
make sure to specify x:Class and include your XAML file as AvaloniaResource

Root Cause: A C# converter class referenced in an .axaml file uses the wrong namespace.
Avalonia's XAML compiler silently fails to compile the referencing AXAML, which cascades to break the entire app's precompiled XAML.

How to diagnose:

• Check any recently added/modified converters under ShareX.ImageEditor/src/ShareX.ImageEditor/UI/Adapters/Converters/

• Verify their C# namespace matches the AXAML xmlns:converters import:

  In EditorView.axaml:

  xmlns:converters="using:ShareX.ImageEditor.Converters"
  

  So all converter classes must declare:

  namespace ShareX.ImageEditor.Converters;
  

Fix:

// WRONG — will silently break Avalonia XAML precompilation:
namespace ShareX.ImageEditor.UI.Adapters.Converters;

// CORRECT — matches the xmlns:converters import in EditorView.axaml:
namespace ShareX.ImageEditor.Converters;

After fixing, rebuild from scratch.

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🔴 Failure: AVLN9999: The process cannot access the file '...XerahS.Imgur.Plugin.pdb' because it is being used by another process

Root Cause: A previous dotnet publish is still running in the background (e.g. from a backgrounded & command).

Fix:

pkill -f "dotnet publish"
pkill -f "package-linux.sh"
sleep 3
bash build/linux/package-linux.sh

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🔴 Failure: MSB3026: Could not copy '...XerahS.Uploaders.dll' ... being used by another process

Root Cause: Parallel plugin publishing is racing to write shared DLLs.

Fix: This is usually a transient retry (MSBuild will retry automatically). If it becomes fatal:

rm -rf src/desktop/core/XerahS.Uploaders/obj/Release
bash build/linux/package-linux.sh

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🔴 Failure: Error: No plugins were published for linux-x64

Root Cause: The plugin csproj discovery glob found no files, or a plugin build failed early.

Check:

find src/desktop/plugins -mindepth 2 -maxdepth 2 -name "*.csproj"

Each plugin project under src/desktop/plugins/ needs a plugin.json in the same directory.

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Phase 4: Validation

After the build completes, verify the artifacts:

ls -lh dist/

Expected output:

XerahS-0.16.1-linux-x64.deb    ~90-120MB
XerahS-0.16.1-linux-arm64.deb  ~90-120MB
XerahS-0.16.1-linux-x64.rpm    ~90-120MB  (if rpmbuild installed)
XerahS-0.16.1-linux-arm64.rpm  ~90-120MB  (if rpmbuild installed)

Timestamps should match the current build session.

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Important Notes

Why Avalonia XAML Precompilation Fails Silently

• Avalonia compiles .axaml files to IL at build time
• If a referenced type (e.g. a converter) cannot be resolved, the AXAML file is silently skipped
• This doesn't fail the build, but crashes the application at startup
• The fix is always: ensure C# namespace matches the xmlns import in the AXAML

Key Build Parameters (from package-linux.sh)

• -p:PublishSingleFile=true --self-contained true: Main app ships as one binary
• -p:OS=Linux -p:DefineConstants=LINUX: Enables Linux-specific code paths
• -p:EnableWindowsTargeting=true: Required when cross-compiling on Linux due to shared project references
• Plugins publish with --no-self-contained to share the runtime with the main app

Sequential Builds Are Mandatory

NEVER run two builds at the same time. ShareX.ImageEditor targets multiple TFMs and MSBuild parallelism causes them to race on the same ShareX.ImageEditor.dll output path.

• Architectures: package-linux.sh iterates linux-x64 then linux-arm64 sequentially — never invoke it twice concurrently.
• Internal parallelism: If CS2012 / file lock errors appear on ShareX.ImageEditor, pre-build it separately with /m:1 to force single-threaded compilation:

  dotnet build ShareX.ImageEditor/src/ShareX.ImageEditor/ShareX.ImageEditor.csproj \
    -c Release -p:UseSharedCompilation=false /m:1
  

• Between builds: Always kill all dotnet and package-linux.sh processes and wait for them to exit before starting a new build session.

Background Build Caution

• Do not background the build script with & unless you redirect output to a log file
• Multiple concurrent builds share obj/ folders and will conflict
• Always kill previous builds before starting a new one

stdout Buffering Issue

• dotnet publish progress may not appear in command_status tool output until the command finishes
• Redirect to a .log file and use view_file to check progress instead of waiting for command output

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Success Criteria

• ✅ Both linux-x64 and linux-arm64 .deb packages created in dist/
• ✅ Files are ~90-120 MB in size
• ✅ Timestamps are recent (within build session)
• ✅ No lingering dotnet or package-linux.sh processes
• ✅ App launches without XamlLoadException at startup

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Troubleshooting

| Symptom | Solution | |---------|----------| | XamlLoadException: No precompiled XAML found at startup | Check namespaces of all new converter classes — must match xmlns:converters in .axaml | | AVLN9999: file used by another process | Kill all dotnet publish and package-linux.sh processes, retry | | MSB3026: Could not copy XerahS.Uploaders.dll | Usually transient; if fatal, delete src/desktop/core/XerahS.Uploaders/obj/Release and retry | | Error: No plugins were published | Check src/desktop/plugins/ structure and plugin.json presence in each plugin directory | | ARM64 cross-compile fails | Ensure linux-arm64 .NET SDK cross-compile support is installed; Fedora needs dotnet-sdk-10.0 | | rpmbuild: command not found | RPM skipped (not fatal); install with sudo dnf install rpm-build if needed | | Build succeeds but app segfaults | SkiaSharp native library issue; verify the current centrally managed SkiaSharp/native-assets set and published runtimes before changing versions |

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Related Files

• Shared guardrails: build-common
• Build script: build/linux/package-linux.sh
• Packaging tool: build/linux/XerahS.Packaging/
• Version config: Directory.Build.props
• Main app project: src/desktop/app/XerahS.App/XerahS.App.csproj
• Converters namespace reference: ShareX.ImageEditor.Converters (match all new converter classes to this)