Resolve absolute path from relative path and/or file name

Is there a way in a Windows batch script to return an absolute path from a value containing a filename and/or relative path?

Given:

"..\"
"..\somefile.txt"

I need the absolute path relative to the batch file.

Example:

• "somefile.txt" is located in "C:\Foo\"
• "test.bat" is located in "C:\Foo\Bar".
• User opens a command window in "C:\Foo" and calls Bar\test.bat ..\somefile.txt
• In the batch file "C:\Foo\somefile.txt" would be derived from %1

In batch files, as in standard C programs, argument 0 contains the path to the currently executing script. You can use %~dp0 to get only the path portion of the 0th argument (which is the current script) - this path is always a fully qualified path.

You can also get the fully qualified path of your first argument by using %~f1, but this gives a path according to the current working directory, which is obviously not what you want.

Personally, I often use the %~dp0%~1 idiom in my batch file, which interpret the first argument relative to the path of the executing batch. It does have a shortcoming though: it miserably fails if the first argument is fully-qualified.

If you need to support both relative and absolute paths, you can make use of Frédéric Ménez's solution: temporarily change the current working directory.

Here's an example that'll demonstrate each of these techniques:

@echo off
echo %%~dp0 is "%~dp0"
echo %%0 is "%0"
echo %%~dpnx0 is "%~dpnx0"
echo %%~f1 is "%~f1"
echo %%~dp0%%~1 is "%~dp0%~1"

rem Temporarily change the current working directory, to retrieve a full path 
rem   to the first parameter
pushd .
cd %~dp0
echo batch-relative %%~f1 is "%~f1"
popd

If you save this as c:\temp\example.bat and the run it from c:\Users\Public as

c:\Users\Public>\temp\example.bat ..\windows

...you'll observe the following output:

%~dp0 is "C:\temp\"
%0 is "\temp\example.bat"
%~dpnx0 is "C:\temp\example.bat"
%~f1 is "C:\Users\windows"
%~dp0%~1 is "C:\temp\..\windows"
batch-relative %~f1 is "C:\Windows"

the documentation for the set of modifiers allowed on a batch argument can be found here: https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/call

I came across a similar need this morning: how to convert a relative path into an absolute path inside a Windows command script.

The following did the trick:

@echo off

set REL_PATH=..\..\
set ABS_PATH=

rem // Save current directory and change to target directory
pushd %REL_PATH%

rem // Save value of CD variable (current directory)
set ABS_PATH=%CD%

rem // Restore original directory
popd

echo Relative path: %REL_PATH%
echo Maps to path: %ABS_PATH%

Most of these answers seem crazy over complicated and super buggy, here's mine -- it works on any environment variable, no %CD% or PUSHD/POPD, or for /f nonsense -- just plain old batch functions. -- The directory & file don't even have to exist.

CALL :NORMALIZEPATH "..\..\..\foo\bar.txt"
SET BLAH=%RETVAL%

ECHO "%BLAH%"

:: ========== FUNCTIONS ==========
EXIT /B

:NORMALIZEPATH
  SET RETVAL=%~f1
  EXIT /B

Without having to have another batch file to pass arguments to (and use the argument operators), you can use FOR /F:

FOR /F %%i IN ("..\relativePath") DO echo absolute path: %%~fi

where the i in %%~fi is the variable defined at /F %%i. eg. if you changed that to /F %%a then the last part would be %%~fa.

To do the same thing right at the command prompt (and not in a batch file) replace %% with %...