[batch-file] Windows Bat file optional argument parsing

I need my bat file to accept multiple optional named arguments.

mycmd.bat man1 man2 -username alice -otheroption

For example my command has 2 mandatory parameters, and two optional parameters (-username) that has an argument value of alice, and -otheroption:

I'd like to be able to pluck these values into variables.

Just putting out a call to anyone that has already solved this. Man these bat files are a pain.

The selected answer works, but it could use some improvement.

• The options should probably be initialized to default values.
• It would be nice to preserve %0 as well as the required args %1 and %2.
• It becomes a pain to have an IF block for every option, especially as the number of options grows.
• It would be nice to have a simple and concise way to quickly define all options and defaults in one place.
• It would be good to support stand-alone options that serve as flags (no value following the option).
• We don't know if an arg is enclosed in quotes. Nor do we know if an arg value was passed using escaped characters. Better to access an arg using %~1 and enclose the assignment within quotes. Then the batch can rely on the absence of enclosing quotes, but special characters are still generally safe without escaping. (This is not bullet proof, but it handles most situations)

My solution relies on the creation of an OPTIONS variable that defines all of the options and their defaults. OPTIONS is also used to test whether a supplied option is valid. A tremendous amount of code is saved by simply storing the option values in variables named the same as the option. The amount of code is constant regardless of how many options are defined; only the OPTIONS definition has to change.

EDIT - Also, the :loop code must change if the number of mandatory positional arguments changes. For example, often times all arguments are named, in which case you want to parse arguments beginning at position 1 instead of 3. So within the :loop, all 3 become 1, and 4 becomes 2.

@echo off
setlocal enableDelayedExpansion

:: Define the option names along with default values, using a <space>
:: delimiter between options. I'm using some generic option names, but 
:: normally each option would have a meaningful name.
::
:: Each option has the format -name:[default]
::
:: The option names are NOT case sensitive.
::
:: Options that have a default value expect the subsequent command line
:: argument to contain the value. If the option is not provided then the
:: option is set to the default. If the default contains spaces, contains
:: special characters, or starts with a colon, then it should be enclosed
:: within double quotes. The default can be undefined by specifying the
:: default as empty quotes "".
:: NOTE - defaults cannot contain * or ? with this solution.
::
:: Options that are specified without any default value are simply flags
:: that are either defined or undefined. All flags start out undefined by
:: default and become defined if the option is supplied.
::
:: The order of the definitions is not important.
::
set "options=-username:/ -option2:"" -option3:"three word default" -flag1: -flag2:"

:: Set the default option values
for %%O in (%options%) do for /f "tokens=1,* delims=:" %%A in ("%%O") do set "%%A=%%~B"

:loop
:: Validate and store the options, one at a time, using a loop.
:: Options start at arg 3 in this example. Each SHIFT is done starting at
:: the first option so required args are preserved.
::
if not "%~3"=="" (
  set "test=!options:*%~3:=! "
  if "!test!"=="!options! " (
    rem No substitution was made so this is an invalid option.
    rem Error handling goes here.
    rem I will simply echo an error message.
    echo Error: Invalid option %~3
  ) else if "!test:~0,1!"==" " (
    rem Set the flag option using the option name.
    rem The value doesn't matter, it just needs to be defined.
    set "%~3=1"
  ) else (
    rem Set the option value using the option as the name.
    rem and the next arg as the value
    set "%~3=%~4"
    shift /3
  )
  shift /3
  goto :loop
)

:: Now all supplied options are stored in variables whose names are the
:: option names. Missing options have the default value, or are undefined if
:: there is no default.
:: The required args are still available in %1 and %2 (and %0 is also preserved)
:: For this example I will simply echo all the option values,
:: assuming any variable starting with - is an option.
::
set -

:: To get the value of a single parameter, just remember to include the `-`
echo The value of -username is: !-username!

There really isn't that much code. Most of the code above is comments. Here is the exact same code, without the comments.

@echo off
setlocal enableDelayedExpansion

set "options=-username:/ -option2:"" -option3:"three word default" -flag1: -flag2:"

for %%O in (%options%) do for /f "tokens=1,* delims=:" %%A in ("%%O") do set "%%A=%%~B"
:loop
if not "%~3"=="" (
  set "test=!options:*%~3:=! "
  if "!test!"=="!options! " (
      echo Error: Invalid option %~3
  ) else if "!test:~0,1!"==" " (
      set "%~3=1"
  ) else (
      set "%~3=%~4"
      shift /3
  )
  shift /3
  goto :loop
)
set -

:: To get the value of a single parameter, just remember to include the `-`
echo The value of -username is: !-username!

This solution provides Unix style arguments within a Windows batch. This is not the norm for Windows - batch usually has the options preceding the required arguments and the options are prefixed with /.

The techniques used in this solution are easily adapted for a Windows style of options.

• The parsing loop always looks for an option at %1, and it continues until arg 1 does not begin with /
• Note that SET assignments must be enclosed within quotes if the name begins with /.
  SET /VAR=VALUE fails
  SET "/VAR=VALUE" works. I am already doing this in my solution anyway.
• The standard Windows style precludes the possibility of the first required argument value starting with /. This limitation can be eliminated by employing an implicitly defined // option that serves as a signal to exit the option parsing loop. Nothing would be stored for the // "option".
  
  

Update 2015-12-28: Support for ! in option values

In the code above, each argument is expanded while delayed expansion is enabled, which means that ! are most likely stripped, or else something like !var! is expanded. In addition, ^ can also be stripped if ! is present. The following small modification to the un-commented code removes the limitation such that ! and ^ are preserved in option values.

@echo off
setlocal enableDelayedExpansion

set "options=-username:/ -option2:"" -option3:"three word default" -flag1: -flag2:"

for %%O in (%options%) do for /f "tokens=1,* delims=:" %%A in ("%%O") do set "%%A=%%~B"
:loop
if not "%~3"=="" (
  set "test=!options:*%~3:=! "
  if "!test!"=="!options! " (
      echo Error: Invalid option %~3
  ) else if "!test:~0,1!"==" " (
      set "%~3=1"
  ) else (
      setlocal disableDelayedExpansion
      set "val=%~4"
      call :escapeVal
      setlocal enableDelayedExpansion
      for /f delims^=^ eol^= %%A in ("!val!") do endlocal&endlocal&set "%~3=%%A" !
      shift /3
  )
  shift /3
  goto :loop
)
goto :endArgs
:escapeVal
set "val=%val:^=^^%"
set "val=%val:!=^!%"
exit /b
:endArgs

set -

:: To get the value of a single parameter, just remember to include the `-`
echo The value of -username is: !-username!

Dynamic variables creation

Pros

• Works for >9 arguments
• Keeps %1, %2, ... %* in tact
• Works for both /arg and -arg style
• No prior knowledge about arguments
• Implementation is separate from main routine

Cons

• Old arguments may leak into consecutive runs, therefore use setlocal for local scoping or write an accompanying :CLEAR-ARGS routine!
• No alias support yet (like --force to -f)
• No empty "" argument support

Usage

Here is an example how the following arguments relate to .bat variables:

>> testargs.bat /b 3 -c /d /e /f /g /h /i /j /k /bar 5 /foo "c:\"

echo %*        | /b 3 -c /d /e /f /g /h /i /j /k /bar 5 /foo "c:\"
echo %ARG_FOO% | c:\
echo %ARG_A%   |
echo %ARG_B%   | 3
echo %ARG_C%   | 1
echo %ARG_D%   | 1

Implementation

@echo off
setlocal

CALL :ARG-PARSER %*

::Print examples
echo: ALL: %*
echo: FOO: %ARG_FOO%
echo: A:   %ARG_A%
echo: B:   %ARG_B%
echo: C:   %ARG_C%
echo: D:   %ARG_D%


::*********************************************************
:: Parse commandline arguments into sane variables
:: See the following scenario as usage example:
:: >> thisfile.bat /a /b "c:\" /c /foo 5
:: >> CALL :ARG-PARSER %*
:: ARG_a=1
:: ARG_b=c:\
:: ARG_c=1
:: ARG_foo=5
::*********************************************************
:ARG-PARSER
    ::Loop until two consecutive empty args
    :loopargs
        IF "%~1%~2" EQU "" GOTO :EOF

        set "arg1=%~1" 
        set "arg2=%~2"
        shift

        ::Allow either / or -
        set "tst1=%arg1:-=/%"
        if "%arg1%" NEQ "" (
            set "tst1=%tst1:~0,1%"
        ) ELSE (
            set "tst1="
        )

        set "tst2=%arg2:-=/%"
        if "%arg2%" NEQ "" (
            set "tst2=%tst2:~0,1%"
        ) ELSE (
            set "tst2="
        )


        ::Capture assignments (eg. /foo bar)
        IF "%tst1%" EQU "/"  IF "%tst2%" NEQ "/" IF "%tst2%" NEQ "" (
            set "ARG_%arg1:~1%=%arg2%"
            GOTO loopargs
        )

        ::Capture flags (eg. /foo)
        IF "%tst1%" EQU "/" (
            set "ARG_%arg1:~1%=1"
            GOTO loopargs
        )
    goto loopargs
GOTO :EOF

Once I had written a program that handle the short (-h), long (--help) and non-option arguments in batch file. This techniques includes:

• non-option arguments followed by a option arguments.

• shift operator for those options that have no argument like '--help'.

• two time shift operator for those options that require an argument.

• loop through a label for processing all command line arguments.

• Exit script and stop processing for those options that no need to require further action like '--help'.

• Wrote help functions for user guidiness

Here is my code.

set BOARD=
set WORKSPACE=
set CFLAGS=
set LIB_INSTALL=true
set PREFIX=lib
set PROGRAM=install_boards

:initial
 set result=false
 if "%1" == "-h" set result=true
 if "%1" == "--help" set result=true
 if "%result%" == "true" (
 goto :usage
 )
 if "%1" == "-b" set result=true
 if "%1" == "--board" set result=true
 if "%result%" == "true" (
 goto :board_list
 )
 if "%1" == "-n" set result=true
 if "%1" == "--no-lib" set result=true
 if "%result%" == "true" (
 set LIB_INSTALL=false
 shift & goto :initial
 )
 if "%1" == "-c" set result=true
 if "%1" == "--cflag" set result=true
 if "%result%" == "true" (
 set CFLAGS=%2
 if not defined CFLAGS (
 echo %PROGRAM%: option requires an argument -- 'c'
 goto :try_usage
 )
 shift & shift & goto :initial
 )
 if "%1" == "-p" set result=true
 if "%1" == "--prefix" set result=true
 if "%result%" == "true" (
 set PREFIX=%2
 if not defined PREFIX (
 echo %PROGRAM%: option requires an argument -- 'p'
 goto :try_usage
 )
 shift & shift & goto :initial
 )

:: handle non-option arguments
set BOARD=%1
set WORKSPACE=%2

goto :eof


:: Help section

:usage
echo Usage: %PROGRAM% [OPTIONS]... BOARD... WORKSPACE
echo Install BOARD to WORKSPACE location.
echo WORKSPACE directory doesn't already exist!
echo.
echo Mandatory arguments to long options are mandatory for short options too.
echo   -h, --help                   display this help and exit
echo   -b, --boards                 inquire about available CS3 boards
echo   -c, --cflag=CFLAGS           making the CS3 BOARD libraries for CFLAGS
echo   -p. --prefix=PREFIX          install CS3 BOARD libraries in PREFIX
echo                                [lib]
echo   -n, --no-lib                 don't install CS3 BOARD libraries by default
goto :eof

:try_usage
echo Try '%PROGRAM% --help' for more information
goto :eof

Here is the arguments parser. You can mix any string arguments (kept untouched) or escaped options (single or option/value pairs). To test it uncomment last 2 statements and run as:

getargs anystr1 anystr2 /test$1 /test$2=123 /test$3 str anystr3

Escape char is defined as "_SEP_=/", redefine if needed.

@echo off

REM Command line argument parser. Format (both "=" and "space" separators are supported):
REM   anystring1 anystring2 /param1 /param2=value2 /param3 value3 [...] anystring3 anystring4
REM Returns enviroment variables as:
REM   param1=1
REM   param2=value2
REM   param3=value3
REM Leading and traling strings are preserved as %1, %2, %3 ... %9 parameters
REM but maximum total number of strings is 9 and max number of leading strings is 8
REM Number of parameters is not limited!

set _CNT_=1
set _SEP_=/

:PARSE

if %_CNT_%==1 set _PARAM1_=%1 & set _PARAM2_=%2
if %_CNT_%==2 set _PARAM1_=%2 & set _PARAM2_=%3
if %_CNT_%==3 set _PARAM1_=%3 & set _PARAM2_=%4
if %_CNT_%==4 set _PARAM1_=%4 & set _PARAM2_=%5
if %_CNT_%==5 set _PARAM1_=%5 & set _PARAM2_=%6
if %_CNT_%==6 set _PARAM1_=%6 & set _PARAM2_=%7
if %_CNT_%==7 set _PARAM1_=%7 & set _PARAM2_=%8
if %_CNT_%==8 set _PARAM1_=%8 & set _PARAM2_=%9

if "%_PARAM2_%"=="" set _PARAM2_=1

if "%_PARAM1_:~0,1%"=="%_SEP_%" (
  if "%_PARAM2_:~0,1%"=="%_SEP_%" (
    set %_PARAM1_:~1,-1%=1
    shift /%_CNT_%
  ) else (
    set %_PARAM1_:~1,-1%=%_PARAM2_%
    shift /%_CNT_%
    shift /%_CNT_%
  )
) else (
  set /a _CNT_+=1
)

if /i %_CNT_% LSS 9 goto :PARSE

set _PARAM1_=
set _PARAM2_=
set _CNT_=

rem getargs anystr1 anystr2 /test$1 /test$2=123 /test$3 str anystr3
rem set | find "test$"
rem echo %1 %2 %3 %4 %5 %6 %7 %8 %9

:EXIT

If you want to use optional arguments, but not named arguments, then this approach worked for me. I think this is much easier code to follow.

REM Get argument values.  If not specified, use default values.
IF "%1"=="" ( SET "DatabaseServer=localhost" ) ELSE ( SET "DatabaseServer=%1" )
IF "%2"=="" ( SET "DatabaseName=MyDatabase" ) ELSE ( SET "DatabaseName=%2" )

REM Do work
ECHO Database Server = %DatabaseServer%
ECHO Database Name   = %DatabaseName%