Check if command is internal in CMD - windows

Question

I have a command's name and I need to check if this command is internal. How can I do it in a batch script?

Answer 1

So after a lot of tweaking, and thanks to the help of #Andriy M, it finally works.
#ECHO off
CALL :isInternalCommand dir dirInternal
ECHO is dir internal: %dirInternal%
CALL :isInternalCommand find findInternal
ECHO is find internal: %findInternal%
exit /b 0
:isInternalCommand
SETLOCAL
MKDIR %TEMP%\EMPTY_DIR_FOR_TEST > NUL 2>& 1
CD /D %TEMP%\EMPTY_DIR_FOR_TEST
SET PATH=
%~1 /? > NUL 2>&1
IF ERRORLEVEL 9009 (ENDLOCAL
SET "%~2=no"
) ELSE (ENDLOCAL
SET "%~2=yes"
)
GOTO :EOF
OLD SOLUTION
You can use where. If it fails, the command is probably internal. If it succeeds, you get the executable path that proves it's not internal.
C:\Users\user>where path
INFO: Could not find files for the given pattern(s).
C:\Users\user>where find
C:\Windows\System32\find.exe
EDIT: As the comments suggest, this might not be the best solution if you're looking for portability and not just research. So here's another possible solution.
Set %PATH% to nothing so HELP can't find anything and then run HELP on the command you're trying to check.
C:\Users\user>set PATH=
C:\Users\user>path
PATH=(null)
C:\Users\user>%WINDIR%\System32\help del
Deletes one or more files.
DEL [/P] [/F] [/S] [/Q] [/A[[:]attributes]] names
[...]
C:\Users\user>%WINDIR%\System32\help find
'find' is not recognized as an internal or external command,
operable program or batch file.
This might still fail if the command doesn't have help.
EDIT 2: Never mind, this won't work either. Both cases return %ERRORLEVEL%=1.

Answer 2

kichik has a good answer. However, it can give a false positive if there happens to be an executable or batch script within the current directory that matches the supplied command name.
The only way I can think of to avoid that problem is to create a folder that is known to be empty within the %TEMP% directory, and then run the test from that folder.
Here is a modified version of kichik's solution that should work.
#echo off
setlocal
::Print the result to the screen
call :isInternal find
call :isInternal dir
::Save the result to a variable
call :isInternal find resultFind
call :isInternal dir resultDir
set result
exit /b
:isInternal command [rtnVar]
setlocal
set "empty=%temp%\empty%random%"
md "%empty%"
pushd "%empty%"
set path=
>nul 2>nul %1 /?
if errorlevel 9009 (set rtn=not internal) else (set rtn=internal)
popd
rd "%empty%"
(
endlocal
if "%~2" neq "" (set %~2=%rtn%) else echo %1 is %rtn%
)
exit /b 0
Here is a script that will simply list all internal commands, assuming that HELP includes a complete list of internal commands.
Update: Both FOR and IF have special parsing rules that prevent those commands from working if executed via a FOR variable or delayed expansion. I had to rewrite this script to use a CALL and execute the command via a CALL argument instead.
#echo off
setlocal enableDelayedExpansion
set "empty=%temp%\empty%random%"
md "%empty%"
pushd "%empty%"
for /f "delims= " %%A in ('help^|findstr /rc:"^[^ ][^ ]* "') do call :test %%A
popd
rd "%empty%"
exit /b
:test
setlocal
set path=
%1 /? >nul 2>nul
if not errorlevel 9009 echo %1
exit /b 0