Batch script interpreting content inside comment?












4














When I run the following batch script:



@echo off
REM %~ will strip surrounding quotes if any

echo HERE


I get the following error:



C:>test.cmd
The following usage of the path operator in batch-parameter
substitution is invalid: %~ will strip surrounding quotes if any

For valid formats type CALL /? or FOR /?


Same effect if REM is changed to ::.



Seems like the parser is ignoring the comment indicator and parsing the %~. If I put a space between the % and ~ then it works fine.



Windows 7 Enterprise (have not checked any other versions).



Seems like a bug to me, but am I missing something?










share|improve this question




















  • 3




    I think that happens in an early parsing phase, for details see how-does-the-windows-command-interpreter-cmd-exe-parse-scripts
    – LotPings
    Nov 21 at 0:59












  • Wow! Just when I thought Batch couldn't be more brain dead, I learn about this, and find a new low. Sigh...
    – codesniffer
    Nov 22 at 1:25
















4














When I run the following batch script:



@echo off
REM %~ will strip surrounding quotes if any

echo HERE


I get the following error:



C:>test.cmd
The following usage of the path operator in batch-parameter
substitution is invalid: %~ will strip surrounding quotes if any

For valid formats type CALL /? or FOR /?


Same effect if REM is changed to ::.



Seems like the parser is ignoring the comment indicator and parsing the %~. If I put a space between the % and ~ then it works fine.



Windows 7 Enterprise (have not checked any other versions).



Seems like a bug to me, but am I missing something?










share|improve this question




















  • 3




    I think that happens in an early parsing phase, for details see how-does-the-windows-command-interpreter-cmd-exe-parse-scripts
    – LotPings
    Nov 21 at 0:59












  • Wow! Just when I thought Batch couldn't be more brain dead, I learn about this, and find a new low. Sigh...
    – codesniffer
    Nov 22 at 1:25














4












4








4







When I run the following batch script:



@echo off
REM %~ will strip surrounding quotes if any

echo HERE


I get the following error:



C:>test.cmd
The following usage of the path operator in batch-parameter
substitution is invalid: %~ will strip surrounding quotes if any

For valid formats type CALL /? or FOR /?


Same effect if REM is changed to ::.



Seems like the parser is ignoring the comment indicator and parsing the %~. If I put a space between the % and ~ then it works fine.



Windows 7 Enterprise (have not checked any other versions).



Seems like a bug to me, but am I missing something?










share|improve this question















When I run the following batch script:



@echo off
REM %~ will strip surrounding quotes if any

echo HERE


I get the following error:



C:>test.cmd
The following usage of the path operator in batch-parameter
substitution is invalid: %~ will strip surrounding quotes if any

For valid formats type CALL /? or FOR /?


Same effect if REM is changed to ::.



Seems like the parser is ignoring the comment indicator and parsing the %~. If I put a space between the % and ~ then it works fine.



Windows 7 Enterprise (have not checked any other versions).



Seems like a bug to me, but am I missing something?







windows batch-file






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 21 at 8:25









michael_heath

2,6292616




2,6292616










asked Nov 21 at 0:08









codesniffer

18611




18611








  • 3




    I think that happens in an early parsing phase, for details see how-does-the-windows-command-interpreter-cmd-exe-parse-scripts
    – LotPings
    Nov 21 at 0:59












  • Wow! Just when I thought Batch couldn't be more brain dead, I learn about this, and find a new low. Sigh...
    – codesniffer
    Nov 22 at 1:25














  • 3




    I think that happens in an early parsing phase, for details see how-does-the-windows-command-interpreter-cmd-exe-parse-scripts
    – LotPings
    Nov 21 at 0:59












  • Wow! Just when I thought Batch couldn't be more brain dead, I learn about this, and find a new low. Sigh...
    – codesniffer
    Nov 22 at 1:25








3




3




I think that happens in an early parsing phase, for details see how-does-the-windows-command-interpreter-cmd-exe-parse-scripts
– LotPings
Nov 21 at 0:59






I think that happens in an early parsing phase, for details see how-does-the-windows-command-interpreter-cmd-exe-parse-scripts
– LotPings
Nov 21 at 0:59














Wow! Just when I thought Batch couldn't be more brain dead, I learn about this, and find a new low. Sigh...
– codesniffer
Nov 22 at 1:25




Wow! Just when I thought Batch couldn't be more brain dead, I learn about this, and find a new low. Sigh...
– codesniffer
Nov 22 at 1:25












2 Answers
2






active

oldest

votes


















3
















The %-expansion, hence expanding normal environment variables (like %VAR%) as well as command line arguments (like %0), is the very first step after having read a line, therefore it happens even before the rem command is recognised. Thus you need to avoid the %~ (by writing rem % + ~ ..., for instance).



Given that the command extensions are enabled, which is the default anyway, %~ is recognised as invalid argument syntax (the ~ is expected to be followed by a decimal digit denoting the argument position or by a valid modifier like f, d, p, n, x, etc.; see Command Line arguments (Parameters)) and results in a fatal error, meaning that an error message is thrown and batch file processing is aborted (the %ErrorLevel% is not set though).



The same effect comes up when you try to do sub-string substitution but specifying an empty search string (like %VAR:=replace% or %VAR:*=replace%, given that VAR is defined), also with command extensions enabled.



See also this thread: How does the Windows Command Interpreter (CMD.EXE) parse scripts?






share|improve this answer































    3














    I think it is clearly covered in quite a few docs that cmd will interpret the arguments before comments, see the example in @LotPings comment as well as @aschiphl's post. That being said, you can momentarily disableextensions and then turn it back on when needed. The below example shows how disabling it will allow you to use it in the REM comment and then enabled again after to show allow extensions:



    @echo off
    setlocal disableextensions
    REM %~ will strip surrounding quotes if any"
    endlocal
    echo my batch file is %~0





    share|improve this answer



















    • 3




      Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
      – aschipfl
      Nov 21 at 9:01










    • @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
      – Gerhard Barnard
      Nov 21 at 9:18










    • Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
      – codesniffer
      Nov 22 at 1:27











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    2 Answers
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    2 Answers
    2






    active

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    active

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    3
















    The %-expansion, hence expanding normal environment variables (like %VAR%) as well as command line arguments (like %0), is the very first step after having read a line, therefore it happens even before the rem command is recognised. Thus you need to avoid the %~ (by writing rem % + ~ ..., for instance).



    Given that the command extensions are enabled, which is the default anyway, %~ is recognised as invalid argument syntax (the ~ is expected to be followed by a decimal digit denoting the argument position or by a valid modifier like f, d, p, n, x, etc.; see Command Line arguments (Parameters)) and results in a fatal error, meaning that an error message is thrown and batch file processing is aborted (the %ErrorLevel% is not set though).



    The same effect comes up when you try to do sub-string substitution but specifying an empty search string (like %VAR:=replace% or %VAR:*=replace%, given that VAR is defined), also with command extensions enabled.



    See also this thread: How does the Windows Command Interpreter (CMD.EXE) parse scripts?






    share|improve this answer




























      3
















      The %-expansion, hence expanding normal environment variables (like %VAR%) as well as command line arguments (like %0), is the very first step after having read a line, therefore it happens even before the rem command is recognised. Thus you need to avoid the %~ (by writing rem % + ~ ..., for instance).



      Given that the command extensions are enabled, which is the default anyway, %~ is recognised as invalid argument syntax (the ~ is expected to be followed by a decimal digit denoting the argument position or by a valid modifier like f, d, p, n, x, etc.; see Command Line arguments (Parameters)) and results in a fatal error, meaning that an error message is thrown and batch file processing is aborted (the %ErrorLevel% is not set though).



      The same effect comes up when you try to do sub-string substitution but specifying an empty search string (like %VAR:=replace% or %VAR:*=replace%, given that VAR is defined), also with command extensions enabled.



      See also this thread: How does the Windows Command Interpreter (CMD.EXE) parse scripts?






      share|improve this answer


























        3












        3








        3








        The %-expansion, hence expanding normal environment variables (like %VAR%) as well as command line arguments (like %0), is the very first step after having read a line, therefore it happens even before the rem command is recognised. Thus you need to avoid the %~ (by writing rem % + ~ ..., for instance).



        Given that the command extensions are enabled, which is the default anyway, %~ is recognised as invalid argument syntax (the ~ is expected to be followed by a decimal digit denoting the argument position or by a valid modifier like f, d, p, n, x, etc.; see Command Line arguments (Parameters)) and results in a fatal error, meaning that an error message is thrown and batch file processing is aborted (the %ErrorLevel% is not set though).



        The same effect comes up when you try to do sub-string substitution but specifying an empty search string (like %VAR:=replace% or %VAR:*=replace%, given that VAR is defined), also with command extensions enabled.



        See also this thread: How does the Windows Command Interpreter (CMD.EXE) parse scripts?






        share|improve this answer
















        The %-expansion, hence expanding normal environment variables (like %VAR%) as well as command line arguments (like %0), is the very first step after having read a line, therefore it happens even before the rem command is recognised. Thus you need to avoid the %~ (by writing rem % + ~ ..., for instance).



        Given that the command extensions are enabled, which is the default anyway, %~ is recognised as invalid argument syntax (the ~ is expected to be followed by a decimal digit denoting the argument position or by a valid modifier like f, d, p, n, x, etc.; see Command Line arguments (Parameters)) and results in a fatal error, meaning that an error message is thrown and batch file processing is aborted (the %ErrorLevel% is not set though).



        The same effect comes up when you try to do sub-string substitution but specifying an empty search string (like %VAR:=replace% or %VAR:*=replace%, given that VAR is defined), also with command extensions enabled.



        See also this thread: How does the Windows Command Interpreter (CMD.EXE) parse scripts?







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 21 at 9:07

























        answered Nov 21 at 1:54









        aschipfl

        18k82654




        18k82654

























            3














            I think it is clearly covered in quite a few docs that cmd will interpret the arguments before comments, see the example in @LotPings comment as well as @aschiphl's post. That being said, you can momentarily disableextensions and then turn it back on when needed. The below example shows how disabling it will allow you to use it in the REM comment and then enabled again after to show allow extensions:



            @echo off
            setlocal disableextensions
            REM %~ will strip surrounding quotes if any"
            endlocal
            echo my batch file is %~0





            share|improve this answer



















            • 3




              Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
              – aschipfl
              Nov 21 at 9:01










            • @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
              – Gerhard Barnard
              Nov 21 at 9:18










            • Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
              – codesniffer
              Nov 22 at 1:27
















            3














            I think it is clearly covered in quite a few docs that cmd will interpret the arguments before comments, see the example in @LotPings comment as well as @aschiphl's post. That being said, you can momentarily disableextensions and then turn it back on when needed. The below example shows how disabling it will allow you to use it in the REM comment and then enabled again after to show allow extensions:



            @echo off
            setlocal disableextensions
            REM %~ will strip surrounding quotes if any"
            endlocal
            echo my batch file is %~0





            share|improve this answer



















            • 3




              Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
              – aschipfl
              Nov 21 at 9:01










            • @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
              – Gerhard Barnard
              Nov 21 at 9:18










            • Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
              – codesniffer
              Nov 22 at 1:27














            3












            3








            3






            I think it is clearly covered in quite a few docs that cmd will interpret the arguments before comments, see the example in @LotPings comment as well as @aschiphl's post. That being said, you can momentarily disableextensions and then turn it back on when needed. The below example shows how disabling it will allow you to use it in the REM comment and then enabled again after to show allow extensions:



            @echo off
            setlocal disableextensions
            REM %~ will strip surrounding quotes if any"
            endlocal
            echo my batch file is %~0





            share|improve this answer














            I think it is clearly covered in quite a few docs that cmd will interpret the arguments before comments, see the example in @LotPings comment as well as @aschiphl's post. That being said, you can momentarily disableextensions and then turn it back on when needed. The below example shows how disabling it will allow you to use it in the REM comment and then enabled again after to show allow extensions:



            @echo off
            setlocal disableextensions
            REM %~ will strip surrounding quotes if any"
            endlocal
            echo my batch file is %~0






            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Nov 21 at 9:18

























            answered Nov 21 at 6:12









            Gerhard Barnard

            6,91631131




            6,91631131








            • 3




              Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
              – aschipfl
              Nov 21 at 9:01










            • @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
              – Gerhard Barnard
              Nov 21 at 9:18










            • Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
              – codesniffer
              Nov 22 at 1:27














            • 3




              Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
              – aschipfl
              Nov 21 at 9:01










            • @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
              – Gerhard Barnard
              Nov 21 at 9:18










            • Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
              – codesniffer
              Nov 22 at 1:27








            3




            3




            Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
            – aschipfl
            Nov 21 at 9:01




            Instead of setlocal enableextensions I would use endlocal to return to the former state (default) and to the former environment, thus having the same state as in the original code...
            – aschipfl
            Nov 21 at 9:01












            @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
            – Gerhard Barnard
            Nov 21 at 9:18




            @aschipfl true yes, I think I just wanted to demonstrate enable and disable, but will change.
            – Gerhard Barnard
            Nov 21 at 9:18












            Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
            – codesniffer
            Nov 22 at 1:27




            Thanks for the workaround idea! Considering the extra lines to work around this, I simply used a valid expression there: %~1.
            – codesniffer
            Nov 22 at 1:27


















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