How to receive a parameter in a batch file

Question

I have asked a question, Use an environment variable to point to an "Open With" program, which received a fantastic answer. To add myapp.exe, residing in %MYAPPSDIR%, to the Open With context menu, I should write in the CLI

reg add "HKCR\Applications\myapp.exe\shell\open\command" /ve /t REG_EXPAND_SZ /d "\"^%MYAPPSDIR^%\myapp\myapp.exe\" \"^%1\"" /f

Now I want to have a .bat file, receiving a parameter, which executes that sentence. E.g., executing regadd.bat myapp.exe would do it. What should the line in the .bat file be?

The points are:

1. How to include the parameter,
2. How to include the parameter with .exe removed (for the directory part),
3. How to avoid expanding %1 that goes into the registry (I do not know how to escape it appropriately).

I found many resources (e.g., How to use `%` in a batch file), but I wouldn't like to tinker with the registry. My bet for 1 and 3 is (still have to work out 2):

reg add "HKCR\Applications\%1\shell\open\command" /ve /t REG_EXPAND_SZ /d "\"^%MYAPPSDIR^%\(%1 with .exe removed)\%1\" \"^%1\"" /f

I could also set the .bat to be run as regadd.bat myapp. In that case, the line would be

reg add "HKCR\Applications\%1.exe\shell\open\command" /ve /t REG_EXPAND_SZ /d "\"^%MYAPPSDIR^%\%1\%1.exe\" \"^%1\"" /f

I am interested in both options.

Answer 1

Batch interpreter parses command line in slightly different manner than pure command line parser (read answers to another question at StackOverflow):

• command line: to avoid expanding %MYAPPSDIR% by command line interpreter, the % percent character should be escaped by the standard CLI escape character (^ caret): ^%MYAPPSDIR^% or ^%1;
• .bat script: to avoid expanding %MYAPPSDIR% or %1 by batch interpreter, the % percent character should be doubled as follows: %%MYAPPSDIR%% and %%1, respectively.

To distinguish parameters supplied to your batch script:

set "par1=%~1"
if "%par1%"=="" (
  echo no parameter supplied
  goto :eof
) else (
  set "par=%par1:.exe=%"
)
if "%par%"=="%par1%" (
  echo .exe not present
) else (
  echo .exe present
)

or (maybe better)

set "par1=%~1"
if "%par1%"=="" (
  echo no parameter supplied
  goto :eof
) else (
  set "par=%par1:~-4%"
)
if /I "%par%"==".exe" (
  echo .exe present
) else (
  echo .exe not present
)

or (maybe the best)

set "par1=%~1"
if "%par1%"=="" (
  echo no parameter supplied
  goto :eof
) else (
  set "par=%~x1"
)
if /I "%par%"==".exe" (
  echo .exe present
) else (
  echo .exe not present
)

Resources (required reading):

• (command reference) An A-Z Index of the Windows CMD command line
• (additional particularities) Windows CMD Shell Command Line Syntax
• (%~1 etc. special page) Command Line arguments (Parameters)
• (%par1:~-4% substring) Variables: extract part of a variable
• (%par1:.exe=%) Variable Edit/Replace

Answer 2

How to do I use the parameter with .exe removed (for the directory part)?

You can use %~n1.

This expands %1 to a file name without the file extension.

---

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 C:\utils\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

Source parameters

---

Further Reading

• An A-Z Index of the Windows CMD command line - An excellent reference for all things Windows cmd line related.
• parameters - A command line argument (or parameter) is any value passed into a batch script.

Answer 3

I will answer the specific question posted: What should the line in the .bat file be?, which was split into 3 necessary steps.

JosefZ answered separately the 3 points leading to the answer. DavidPostill gave another option for point 2.

The resulting code would be

set "app1=%~1"
if "%app1%"=="" (
  echo No parameter supplied. This should be run as
  echo   regadd.bat myapp.exe
  echo or
  echo   regadd.bat myapp
  goto :eof
) else (
  REM set "app=%app1:.exe=%"
  set "app=%~n1"
)
if "%app%"=="%app1%" (
  REM echo .exe not present
) else (
  REM echo .exe present
)
echo App is %app%
reg add "HKCR\Applications\%app%.exe\shell\open\command" /ve /t REG_EXPAND_SZ /d "\"%%MYAPPSDIR%%\%app%\%app%.exe\" \"%%1\"" /f