Why Does %~dp0 Yield Different Results When a Batch File is Executed Directly vs. via C#?

%~dp0 path reference difference in batch file

Background:

In the batch file, %~dp0 represents the directory path of the current location of the batch file. When changing the current directory (CD), it is generally expected that the value of %~dp0 will be updated to reflect the new directory.

Question:

However, users have observed differences in the behavior of %~dp0 when executing a batch file through a C# program. %~dp0 retains its original value when executed directly, but changes when called from C#.

Analysis:

This difference is due to the way %~0 (the unmodified batch file name) is handled when the batch file is called with quotes.

• Direct execution: When %~0 is quoted, the quotes are removed and the full batch file path is used to determine %~dp0.
• C# execution: When %~0 is quoted in C#, the unquoted string will be used to locate the batch file. This may result in relative paths, resulting in inaccurate %~dp0 values.

Solution:

In order to solve this problem, two methods are recommended:

From C# code:

• Avoid using quotes when calling batch files: ProcessStartInfo.FileName = "mybatfile.bat";
• If quotes are required, please specify the full batch file path to ensure %~dp0 remains accurate.

From batch file:

• Use a subroutine to reliably retrieve the current batch file path regardless of execution method:

@echo off
    setlocal enableextensions disabledelayedexpansion

    call :getCurrentBatch batch
    echo %batch%

    exit /b

:getCurrentBatch variableName
    set "%~1=%~f0"
    goto :eof

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