How-to: Pass Command Line arguments (Parameters) to a Windows batch file.

How-to: Pass Command Line arguments (Parameters) to a Windows batch file.

A command line argument (or parameter) is any value passed into a batch script:

C:> MyScript.cmd January 1234 "Some value"

Arguments can also be passed to a subroutine with CALL:

CALL :my_sub 2468

You can get the value of any argument using a % followed by it's numerical position on the command line. The first item passed is always %1 the second item is always %2 and so on

%* in a batch script refers to all the arguments (e.g. %1 %2 %3 %4 %5 ...%255)
only arguments %1 to %9 can be referenced by number.

Parameter Extensions

When an argument is used to supply a filename then the following extended syntax can be applied:

we are using the variable %1 (but this works for any parameter)

%~f1 Expand %1 to a Fully qualified path name - C:\utils\MyFile.txt

%~d1 Expand %1 to a Drive letter only - C:

%~p1 Expand %1 to a Path only e.g. \utils\ this includes a trailing \ which will be interpreted as an escape character by some commands.

%~n1 Expand %1 to a file Name without file extension or path - MyFile
or if only a path is present, with no trailing backslash, the last folder in that path.

%~x1 Expand %1 to a file eXtension only - .txt

%~s1 Change the meaning of f, n, s and x to reference the Short 8.3 name (if it exists.)

%~1   Expand %1 removing any surrounding quotes (")

%~a1 Display the file attributes of %1

%~t1 Display the date/time of %1

%~z1 Display the file size of %1

%~$PATH:1 Search the PATH environment variable and expand %1 to the fully qualified name of the first match found.

The modifiers above can be combined:

%~dp1 Expand %1 to a drive letter and path only

%~sp1 Expand %1 to a path shortened to 8.3 characters

%~nx2 Expand %2 to a file name and extension only

These parameter/ argument variables are always denoted with a single leading %
This is unlike regular variables which have both leading and trailing %'s such as %variable%, or FOR command variables which use a single leading % on the command line or a double leading %% when used in a batch file.

Parameter expansion will treat a Full Stop within a directory name as a file extension, so for a name like "Sample 2.6.4" the output of %~n1 will be truncated to "Sample 2.6" to return the whole folder name use %1 or %~nx1

If the output of DIR, or a filename with no drive letter/path is expanded to display a Full pathname %~f1 the command shell will assume; often incorrectly; that the file resides in the current directory. The CMD shell does not read file descriptors, or work with filesystem objects the way that PowerShell does, it is processing a simple list of text strings.

When writing batch scripts it's a good idea to store the values in a named variable SET _LogFile=%~dp1, the rest of the script can then refer to the easy-to-read variable name %_LogFile% This will also make life easier if you later need to change around the order of the parameters.

Tokenization

Tokenization of the command line arguments is not always done by the cmd.exe shell. Most often the tokenization is done by the newly formed processes' runtime, at the OS level, Windows passes a command line untokenized as a single string to the new process. You can read more about the low-level details of the batch language/cmd escaping from the excellent answers by jeb and dbenham on this StackOverflow question.

Passing by Reference

In addition to passing numeric or string values on the command line, it is also possible to pass a variable name and then use the variable to transfer data between scripts or subroutines. Passing by reference is a slightly more advanced technique but can be particularly useful when the string contains characters that are CMD delimiters or quotes.

Links relative to the Batch Script

You can get the pathname of the batch script itself with %0, parameter extensions can be applied to this so %~dp0 will return the Drive and Path to the batch script e.g. W:\scripts\ and %~f0 will return the full pathname W:\scripts\mybatch.cmd

You can refer to other files in the same folder as the batch script by using this syntax:

  CALL %0\..\SecondBatch.cmd

This can even be used in a subroutine, Echo %0 will give the call label but, echo "%~nx0" will give you the filename of the batch script.

When the %0 variable is expanded, the result is enclosed in quotation marks.

Use %~a1 to display the Extended Attributes of a file.

FOR's %%~aI recognizes 9 NTFS file attributes. The expansion of a file attribute produces a series of 9 dashes, with each recognized attribute replacing a dash with a letter. A file with no recognized attributes or with none set will expand to 9 dashes like this: ---------

 Attribute                    Expansion 
 FILE_ATTRIBUTE_DIRECTORY     d-------- 
 FILE_ATTRIBUTE_READONLY      -r------- 
 FILE_ATTRIBUTE_ARCHIVE       --a------ 
 FILE_ATTRIBUTE_HIDDEN        ---h----- 
 FILE_ATTRIBUTE_SYSTEM        ----s---- 
 FILE_ATTRIBUTE_COMPRESSED    -----c--- 
 FILE_ATTRIBUTE_OFFLINE       ------o-- 
 FILE_ATTRIBUTE_TEMPORARY     -------t- 
 FILE_ATTRIBUTE_REPARSE_POINT --------l
 FILE_ATTRIBUTE_NORMAL        --------- 

Other NTFS attributes not recognised by %%~aI can be read using FSUTIL usn command:
FILE_ATTRIBUTE_ENCRYPTED
FILE_ATTRIBUTE_NOT_CONTENT_INDEXED
FILE_ATTRIBUTE_SPARSE_FILE

Example: Expansion of a file with the Hidden and System attributes:
---hs----

Maximum line length

The maximum length of any command line (or variable) within CMD is 8191 characters.

Terminology: Command-line Argument or Parameter?

In mathematical terms a parameter is "a numerical or other measurable factor" so typically a number.

In programming terminology:
A parameter represents a value that the procedure expects you to pass when you call it.
An argument represents the actual value that you pass to a procedure.

In practice the phrases argument and parameter tend to be used interchangeably, CMD batch files do not perform any type checking.

FOR parameters

The FOR command creates parameter variables which are identified with a letter rather than a number (e.g. %%G).
The Parameter Expansions described above can also be applied to these.
To avoid confusion between the two sets of letters, avoid using the letters (a, d, f, n, p, s, t, x, z) as FOR parameters or just choose a FOR parameter letter that is UPPER case.
So for example in a reference like %%~fG the %%G is the FOR parameter, and the ~f is the Parameter Expansion.

Examples:

Pass parameters from one batch to another:

   MyBatch.cmd SMITH 100

Or as part of a CALL :

   CALL MyBatch.cmd SMITH 100

Get the file size of C:\demo\sample.xlsx using the %~z parameter extension:

   @Echo off
   For %%G in ("C:\demo\sample.xlsx") do set _var=%%~zG
   Echo File size is %_var%

Passing values from one part of a script to another:

   :: Using CALL to jump to a subroutine
   CALL :s_staff SMITH 100

   :: Calling a subroutine from a FOR command
   FOR /F %%G IN ('DIR /b *.*') DO call :s_subroutine %%G

“I came here for a good argument, No you didn't, you came here for an argument” ~ Monty Python