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Property functions

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Property functions are calls to .NET Framework methods that appear in MSBuild property definitions. Unlike tasks, property functions can be used outside of targets. Property functions are evaluated whenever the properties or items get expanded, which is before any target runs for properties and items outside of any targets, or when the target is evaluated, for property groups and item groups inside targets.

Without using MSBuild tasks, you can read the system time, compare strings, match regular expressions, and perform other actions in your build script. MSBuild will try to convert string to number and number to string, and make other conversions as required.

String values returned from property functions have special characters escaped. If you want the value to be treated as though it was put directly in the project file, use $([MSBuild]::Unescape()) to unescape the special characters.

Property functions are available with .NET Framework 4 and later.

Property function syntax

These are three kinds of property functions; each function has a different syntax:

  • String (instance) property functions
  • Static property functions
  • MSBuild property functions

String property functions

All build property values are just string values. You can use string (instance) methods to operate on any property value. For example, you can extract the drive name (the first three characters) from a build property that represents a full path by using this code:

$(ProjectOutputFolder.Substring(0,3))

Static property functions

In your build script, you can access the static properties and methods of many system classes. To get the value of a static property, use the following syntax, where <Class> is the name of the system class and <Property> is the name of the property.

$([Class]::Property)

For example, you can use the following code to set a build property to the current date and time.

<Today>$([System.DateTime]::Now)</Today>

To call a static method, use the following syntax, where <Class> is the name of the system class, <Method> is the name of the method, and (<Parameters>) is the parameter list for the method:

$([Class]::Method(Parameters))

For example, to set a build property to a new GUID, you can use this script:

<NewGuid>$([System.Guid]::NewGuid())</NewGuid>

In static property functions, you can use any static method or property of these system classes:

In addition, you can use the following static methods and properties:

Calling instance methods on static properties

If you access a static property that returns an object instance, you can invoke the instance methods of that object. To invoke an instance method, use the following syntax, where <Class> is the name of the system class, <Property> is the name of the property, <Method> is the name of the method, and (<Parameters>) is the parameter list for the method:

$([Class]::Property.Method(Parameters))

The name of the class must be fully qualified with the namespace.

For example, you can use the following code to set a build property to the current date today.

<Today>$([System.DateTime]::Now.ToString('yyyy.MM.dd'))</Today>

MSBuild property functions

Several static methods in your build can be accessed to provide arithmetic, bitwise logical, and escape character support. You access these methods by using the following syntax, where <Method> is the name of the method and (<Parameters>) is the parameter list for the method.

$([MSBuild]::Method(Parameters))

For example, to add together two properties that have numeric values, use the following code.

$([MSBuild]::Add($(NumberOne), $(NumberTwo)))

Here is a list of MSBuild property functions:

Function signature Description
double Add(double a, double b) Add two doubles.
long Add(long a, long b) Add two longs.
double Subtract(double a, double b) Subtract two doubles.
long Subtract(long a, long b) Subtract two longs.
double Multiply(double a, double b) Multiply two doubles.
long Multiply(long a, long b) Multiply two longs.
double Divide(double a, double b) Divide two doubles.
long Divide(long a, long b) Divide two longs.
double Modulo(double a, double b) Modulo two doubles.
long Modulo(long a, long b) Modulo two longs.
string Escape(string unescaped) Escape the string according to MSBuild escaping rules.
string Unescape(string escaped) Unescape the string according to MSBuild escaping rules.
int BitwiseOr(int first, int second) Perform a bitwise OR on the first and second (first | second).
int BitwiseAnd(int first, int second) Perform a bitwise AND on the first and second (first & second).
int BitwiseXor(int first, int second) Perform a bitwise XOR on the first and second (first ^ second).
int BitwiseNot(int first) Perform a bitwise NOT (~first).
bool IsOsPlatform(string platformString) Specify whether the current OS platform is platformString. platformString must be a member of OSPlatform.
bool IsOSUnixLike() True if current OS is a Unix system.
string NormalizePath(params string[] path) Gets the canonicalized full path of the provided path and ensures it contains the correct directory separator characters for the current operating system.
string NormalizeDirectory(params string[] path) Gets the canonicalized full path of the provided directory and ensures it contains the correct directory separator characters for the current operating system while ensuring it has a trailing slash.
string EnsureTrailingSlash(string path) If the given path doesn't have a trailing slash then add one. If the path is an empty string, does not modify it.
string GetPathOfFileAbove(string file, string startingDirectory) Searches for and returns the full path to a file in the directory structure above the current build file's location, or based on startingDirectory, if specified.
GetDirectoryNameOfFileAbove(string startingDirectory, string fileName) Locate and return the directory of a file in either the directory specified or a location in the directory structure above that directory.
string MakeRelative(string basePath, string path) Makes path relative to basePath. basePath must be an absolute directory. If path cannot be made relative, it is returned verbatim. Similar to Uri.MakeRelativeUri.
string ValueOrDefault(string conditionValue, string defaultValue) Return the string in parameter 'defaultValue' only if parameter 'conditionValue' is empty, else, return the value conditionValue.

Nested property functions

You can combine property functions to form more complex functions, as the following example shows.

$([MSBuild]::BitwiseAnd(32, $([System.IO.File]::GetAttributes(tempFile))))

This example returns the value of the FileAttributes.Archive bit (32 or 0) of the file given by the path tempFile. Notice that enumerated data values cannot appear by name in some contexts. In the previous example, the numeric value (32) must be used instead. In other cases, depending on the expectations of the method called, the enum data value must be used. In the following example, the enum value RegexOptions.ECMAScript must be used because a numeric value cannot be converted as this method expects.

<PropertyGroup>
    <GitVersionHeightWithOffset>$([System.Text.RegularExpressions.Regex]::Replace("$(PrereleaseVersion)", "^.*?(\d+)$", "$1", "System.Text.RegularExpressions.RegexOptions.ECMAScript"))</GitVersionHeightWithOffset>
</PropertyGroup>

Metadata may also appear in nested property functions. For more information, see Batching.

MSBuild DoesTaskHostExist

The DoesTaskHostExist property function in MSBuild returns whether a task host is currently installed for the specified runtime and architecture values.

This property function has the following syntax:

$([MSBuild]::DoesTaskHostExist(string theRuntime, string theArchitecture))

MSBuild EnsureTrailingSlash

The EnsureTrailingSlash property function in MSBuild adds a trailing slash if one doesn't already exist.

This property function has the following syntax:

$([MSBuild]::EnsureTrailingSlash('$(PathProperty)'))

MSBuild GetDirectoryNameOfFileAbove

The MSBuild GetDirectoryNameOfFileAbove property function searches upward for a directory containing the specified file, beginning in (and including) the specified directory. It returns the full path of the nearest directory containing the file if it is found, otherwise an empty string.

This property function has the following syntax:

$([MSBuild]::GetDirectoryNameOfFileAbove(string startingDirectory, string fileName))

This example shows how to import the nearest EnlistmentInfo.props file in or above the current folder, only if a match is found:

<Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), EnlistmentInfo.props))\EnlistmentInfo.props" Condition=" '$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), EnlistmentInfo.props))' != '' " />

Note that this example can be written more concisely by using the GetPathOfFileAbove function instead:

<Import Project="$([MSBuild]::GetPathOfFileAbove(EnlistmentInfo.props))" Condition=" '$([MSBuild]::GetPathOfFileAbove(EnlistmentInfo.props))' != '' " />

MSBuild GetPathOfFileAbove

The MSBuild GetPathOfFileAbove property function searches upward for a directory containing the specified file, beginning in (and including) the specified directory. It returns the full path of the nearest matching file if it is found, otherwise an empty string.

This property function has the following syntax:

$([MSBuild]::GetPathOfFileAbove(string file, [string startingDirectory]))

where file is the name of the file to search for and startingDirectory is an optional directory to start the search in. By default, the search will start in the current file's own directory.

This example shows how to import a file named dir.props in or above the current directory, only if a match is found:

<Import Project="$([MSBuild]::GetPathOfFileAbove(dir.props))" Condition=" '$([MSBuild]::GetPathOfFileAbove(dir.props))' != '' " />

which is functionally equivalent to

<Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" Condition=" '$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))' != '' " />

However, sometimes you need to start the search in the parent directory, to avoid matching the current file. This example shows how a Directory.Build.props file can import the nearest Directory.Build.props file in a strictly higher level of the tree, without recursively importing itself:

<Import Project="$([MSBuild]::GetPathOfFileAbove('Directory.Build.props', '$(MSBuildThisFileDirectory)../'))" />

which is functionally equivalent to

<Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove('$(MSBuildThisFileDirectory)../', 'Directory.Build.props'))/Directory.Build.props" />

MSBuild GetRegistryValue

The MSBuild GetRegistryValue property function returns the value of a registry key. This function takes two arguments, the key name and the value name, and returns the value from the registry. If you don't specify a value name, the default value is returned.

The following examples show how this function is used:

$([MSBuild]::GetRegistryValue(`HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\10.0\Debugger`, ``))                                  // default value
$([MSBuild]::GetRegistryValue(`HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\10.0\Debugger`, `SymbolCacheDir`))
$([MSBuild]::GetRegistryValue(`HKEY_LOCAL_MACHINE\SOFTWARE\(SampleName)`, `(SampleValue)`))             // parens in name and value

Warning

In the .NET SDK version of MSBuild (dotnet build), this function is not supported.

MSBuild GetRegistryValueFromView

The MSBuild GetRegistryValueFromView property function gets system registry data given the registry key, value, and one or more ordered registry views. The key and value are searched in each registry view in order until they are found.

The syntax for this property function is:

[MSBuild]::GetRegistryValueFromView(string keyName, string valueName, object defaultValue, params object[] views)

The Windows 64-bit operating system maintains a HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node registry key that presents a HKEY_LOCAL_MACHINE\SOFTWARE registry view for 32-bit applications.

By default, a 32-bit application running on WOW64 accesses the 32-bit registry view and a 64-bit application accesses the 64-bit registry view.

The following registry views are available:

Registry view Definition
RegistryView.Registry32 The 32-bit application registry view.
RegistryView.Registry64 The 64-bit application registry view.
RegistryView.Default The registry view that matches the process that the application is running on.

The following is an example.

$([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SDKs\Silverlight\v3.0\ReferenceAssemblies', 'SLRuntimeInstallPath', null, RegistryView.Registry64, RegistryView.Registry32))

gets the SLRuntimeInstallPath data of the ReferenceAssemblies key, looking first in the 64-bit registry view and then in the 32-bit registry view.

Warning

In the .NET SDK version of MSBuild (dotnet build), this function is not supported.

MSBuild MakeRelative

The MSBuild MakeRelative property function returns the relative path of the second path relative to first path. Each path can be a file or folder.

This property function has the following syntax:

$([MSBuild]::MakeRelative($(FileOrFolderPath1), $(FileOrFolderPath2)))

The following code is an example of this syntax.

<PropertyGroup>
    <Path1>c:\users\</Path1>
    <Path2>c:\users\username\</Path2>
</PropertyGroup>

<Target Name = "Go">
    <Message Text ="$([MSBuild]::MakeRelative($(Path1), $(Path2)))" />
    <Message Text ="$([MSBuild]::MakeRelative($(Path2), $(Path1)))" />
</Target>

<!--
Output:
   username\
   ..\
-->

MSBuild ValueOrDefault

The MSBuild ValueOrDefault property function returns the first argument, unless it's null or empty. If the first argument is null or empty, the function returns the second argument.

The following example shows how this function is used.

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

    <PropertyGroup>
        <Value1>$([MSBuild]::ValueOrDefault('$(UndefinedValue)', 'a'))</Value1>
        <Value2>$([MSBuild]::ValueOrDefault('b', '$(Value1)'))</Value2>
    </PropertyGroup>

    <Target Name="MyTarget">
        <Message Text="Value1 = $(Value1)" />
        <Message Text="Value2 = $(Value2)" />
    </Target>
</Project>

<!--
Output:
  Value1 = a
  Value2 = b
-->

MSBuild TargetFramework and TargetPlatform functions

MSBuild 16.7 and higher define several functions for handling TargetFramework and TargetPlatform properties.

Function signature Description
GetTargetFrameworkIdentifier(string targetFramework) Parse the TargetFrameworkIdentifier from the TargetFramework.
GetTargetFrameworkVersion(string targetFramework, int versionPartCount) Parse the TargetFrameworkVersion from the TargetFramework.
GetTargetPlatformIdentifier(string targetFramework) Parse the TargetPlatformIdentifier from the TargetFramework.
GetTargetPlatformVersion(string targetFramework, int versionPartCount) Parse the TargetPlatformVersion from the TargetFramework.
IsTargetFrameworkCompatible(string targetFrameworkTarget, string targetFrameworkCandidate) Return 'True' if the candidate target framework is compatible with this target framework and false otherwise.

The versionPartCount parameter of GetTargetFrameworkVersion and GetTargetPlatformVersion has a default value of 2.

The following example shows how these functions are used.

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

    <PropertyGroup>
        <Value1>$([MSBuild]::GetTargetFrameworkIdentifier('net5.0-windows7.0'))</Value1>
        <Value2>$([MSBuild]::GetTargetFrameworkVersion('net5.0-windows7.0'))</Value2>
        <Value3>$([MSBuild]::GetTargetPlatformIdentifier('net5.0-windows7.0'))</Value3>
        <Value4>$([MSBuild]::GetTargetPlatformVersion('net5.0-windows7.0'))</Value4>
        <Value5>$([MSBuild]::IsTargetFrameworkCompatible('net5.0-windows', 'net5.0'))</Value5>
    </PropertyGroup>

    <Target Name="MyTarget">
        <Message Text="Value1 = $(Value1)" />
        <Message Text="Value2 = $(Value2)" />
        <Message Text="Value3 = $(Value3)" />
        <Message Text="Value4 = $(Value4)" />
        <Message Text="Value5 = $(Value5)" />
    </Target>
</Project>

Value1 = .NETCoreApp
Value2 = 5.0
Value3 = windows
Value4 = 7.0
Value5 = True

MSBuild version-comparison functions

MSBuild 16.5 and higher define several functions for comparing strings that represent versions.

Note

Comparison operators in conditions can compare strings that can be parsed as System.Version objects, but the comparison can produce unexpected results. Prefer the property functions.

Function signature Description
VersionEquals(string a, string b) Return true if versions a and b are equivalent according to the below rules.
VersionGreaterThan(string a, string b) Return true if version a is greater than b according to the below rules.
VersionGreaterThanOrEquals(string a, string b) Return true if version a is greater than or equal to b according to the below rules.
VersionLessThan(string a, string b) Return true if version a is less than b according to the below rules.
VersionLessThanOrEquals(string a, string b) Return true if version a is less than or equal to b according to the below rules.
VersionNotEquals(string a, string b) Return false if versions a and b are equivalent according to the below rules.

In these methods, versions are parsed like System.Version, with the following exceptions:

  • Leading v or V is ignored, which allows comparison to $(TargetFrameworkVersion).

  • Everything from the first '-' or '+' to the end of the version string is ignored. This allows passing in semantic versions (semver), though the order is not the same as semver. Instead, prerelease specifiers and build metadata do not have any sorting weight. This can be useful, for example, to turn on a feature for >= x.y and have it kick in on x.y.z-pre.

  • Unspecified parts are same as zero value parts. (x == x.0 == x.0.0 == x.0.0.0).

  • Whitespace is not allowed in integer components.

  • Major version only is valid (3 is equal to 3.0.0.0)

  • + is not allowed as positive sign in integer components (it is treated as semver metadata and ignored)

Tip

Comparisons of TargetFramework properties should generally use IsTargetFrameworkCompatible instead of extracting and comparing versions. This allows comparing TargetFrameworks that vary in TargetFrameworkIdentifier as well as version.

MSBuild condition functions

The functions Exists and HasTrailingSlash are not property functions. They are available for use with the Condition attribute. See MSBuild conditions.

See also