What does %~dp0 mean, and how does it work?
%~dp0 very useful, and I use it a lot to make my batch files more portable.
But the label itself seems very cryptic to me... What is the
~ doing? Does
dp mean drive and path? Does the
0 refer to
%0, the path to the batch file that includes the file name?
Or it is just a weird label?
I'd also like to know if it is a documented feature, or something prone to be deprecated.
in the command-line gives help about this syntax (which can be used outside FOR, too, this is just the place where help can be found).
In addition, substitution of FOR variable references has been enhanced. You can now use the following optional syntax:
%~I - expands %I removing any surrounding quotes (") %~fI - expands %I to a fully qualified path name %~dI - expands %I to a drive letter only %~pI - expands %I to a path only %~nI - expands %I to a file name only %~xI - expands %I to a file extension only %~sI - expanded path contains short names only %~aI - expands %I to file attributes of file %~tI - expands %I to date/time of file %~zI - expands %I to size of file %~$PATH:I - searches the directories listed in the PATH environment variable and expands %I to the fully qualified name of the first one found. If the environment variable name is not defined or the file is not found by the search, then this modifier expands to the empty string
The modifiers can be combined to get compound results:
%~dpI - expands %I to a drive letter and path only %~nxI - expands %I to a file name and extension only %~fsI - expands %I to a full path name with short names only %~dp$PATH:I - searches the directories listed in the PATH environment variable for %I and expands to the drive letter and path of the first one found. %~ftzaI - expands %I to a DIR like output line
In the above examples %I and PATH can be replaced by other valid values. The %~ syntax is terminated by a valid FOR variable name. Picking upper case variable names like %I makes it more readable and avoids confusion with the modifiers, which are not case sensitive.
There are different letters you can use like
f for "full path name",
d for drive letter,
p for path, and they can be combined.
%~ is the beginning for each of those sequences and a number
I denotes it works on the parameter
%0 is the complete name of the batch file, just like you assumed).
Read more… Read less…
(First, I'd like to recommend this useful reference site for batch: http://ss64.com/nt/)
Then just another useful explanation: http://htipe.wordpress.com/2008/10/09/the-dp0-variable/
The %~dp0 Variable
The %~dp0 (that’s a zero) variable when referenced within a Windows batch file will expand to the drive letter and path of that batch file.
The variables %0-%9 refer to the command line parameters of the batch file. %1-%9 refer to command line arguments after the batch file name. %0 refers to the batch file itself.
If you follow the percent character (%) with a tilde character (~), you can insert a modifier(s) before the parameter number to alter the way the variable is expanded. The d modifier expands to the drive letter and the p modifier expands to the path of the parameter.
Example: Let’s say you have a directory on C: called bat_files, and in that directory is a file called example.bat. In this case, %~dp0 (combining the d and p modifiers) will expand to C:\bat_files.
Check out this Microsoft article for a full explanation.
Also, check out this forum thread.
And a more clear reference from here:
%CmdCmdLine%will return the entire command line as passed to CMD.EXE
%*will return the remainder of the command line starting at the first command line argument (in Windows NT 4, %* also includes all leading spaces)
%~dnwill return the drive letter of %n (n can range from 0 to 9) if %n is a valid path or file name (no UNC)
%~pnwill return the directory of %n if %n is a valid path or file name (no UNC)
%~nnwill return the file name only of %n if %n is a valid file name
%~xnwill return the file extension only of %n if %n is a valid file name
%~fnwill return the fully qualified path of %n if %n is a valid file name or directory
Just found some good reference for the mysterious
~ tilde operator.
%~ string is called percent tilde operator. You can find it in situations like:
:~ string is called colon tilde operator. You can find it like
ADD 2 - 1:12 PM 7/6/2018
%1-%9 refer to the command line args. If they are not valid path values,
%~dp9 will all expand to the same value as
%~dp0. But if they are valid path values, they will expand to their own driver/path value.
For example: (batch.bat)
@echo off @echo ~dp0= %~dp0 @echo ~dp1= %~dp1 @echo ~dp2= %~dp2 @echo on
D:\Workbench>batch arg1 arg2 ~dp0= D:\Workbench\ ~dp1= D:\Workbench\ ~dp2= D:\Workbench\
D:\Workbench>batch c:\123\a.exe e:\abc\b.exe ~dp0= D:\Workbench\ ~dp1= c:\123\ ~dp2= e:\abc\
%0 in a batch script is set to the name of the executing batch file.
~dp special syntax between the
% and the
0 basically says to expand the variable
%0 to show the drive letter and path, which gives you the current directory containing the batch file!
Help = Link
%~dp0 expands to current directory path of the running batch file.
To get clear understanding, let's create a batch file in a directory.
@echo off echo %~dp0
When you run it from command prompt, you will see this result:
Another tip that would help a lot is that to set the current directory to a different drive one would have to use
%~d0 first, then
cd %~dp0. This will change the directory to the batch file's drive, then change to its folder.
Alternatively, for #oneLinerLovers, as @Omni pointed out in the comments
cd /d %~dp0 will change both the drive and directory :)
Hope this helps someone.
Great example from Strawberry Perl's portable shell launcher:
set drive=%~dp0 set drivep=%drive% if #%drive:~-1%# == #\# set drivep=%drive:~0,-1% set PATH=%drivep%\perl\site\bin;%drivep%\perl\bin;%drivep%\c\bin;%PATH%
not sure what the negative 1's doing there myself, but it works a treat!