%~dp0 vs %cd%

Hello,

Just wondering what's the difference in using %~dp0 or %cd% to find the current directory, since I'm not sure that either one will work in every case. Or do both work exactly the same?

Thanks.

They are not equivalent.

%cd% is available either to a batch file or at the command prompt and expands to the drive letter and path of the current directory (which can change e.g. by using the CD command)

%~dp0 is only available within a batch file and expands to the drive letter and path in which that batch file is located (which cannot change). It is obtained from %0 which is the batch file's name.

An experiment like the following shows the difference

Here is D:\dirshow.bat:

Code: [Select]

@echo off
echo this is %%cd%%  %cd%
echo this is %%~dp0 %~dp0

Run it from C:\ and this is what you see

Code: [Select]

C:\>D:\dirshow.bat
this is %cd%  C:\
this is %~dp0 D:\