syntax for Cygwin bash invoking Win apps

[Ziser, Jesse]

>On 09/08/2009 11:30 PM, Ziser, Jesse wrote:
>> Hello list,
>>
>> When I type a command in bash to invoke a Windows application (like
>> cmd.exe, for example), I can't seem to find a pattern in the Windows command
>> line that actually gets executed. Ordinary bash syntax does not seem to
>> apply in general when the command is a Windows app, but rather, sometimes
>> special characters are interpreted in a bash-like way, and sometimes not.
>> So, I'm wondering what determines whether a quote mark or something gets
>> interpreted or passed on.
>>
>> Here are some examples:
>>
>> $ cmd /c echo "/?"
>> Displays messages, or turns command-echoing on or off.
>>
>>    ECHO [ON | OFF]
>>    ECHO [message]
>>
>> Type ECHO without parameters to display the current echo setting.
>>
>> # OK, so I'm getting the Windows echo, not the bash echo.  Good.
>> # Moving on...
>> $ cmd /c echo abc
>> abc
>>
>> $ cmd /c echo "abc"
>> abc
>>
>> $ cmd /c echo "\"abc\""
>> "\"abc\""
>>
>> # Wahhh?!
>>
>> Anyone who knows the explanation would make me very grateful. I've tried
>> this with other Windows apps too, and the same weirdness seems to occur.
>
>All of the above is consistent with bash shell quoting.  It's the shell that 
>does the interpreting in the Unix/Linux world and that's what you're seeing here.

Huh?  Last time I checked, bash translates "\"abc\"" to "abc".

>> On a related note, I've noticed what appears to be an automatic sort of
>half-bash invocation (but not quite?) or something when I run Cygwin
>commands from cmd.exe. For example,
>
>>> c:\cygwin\bin\echo hi
>> hi
>>
>>> c:\cygwin\bin\echo "hi"
>> hi
>>
>>> c:\cygwin\bin\echo "\"hi\""
>> "hi"
>>
>>> c:\cygwin\bin\echo *
>> myfile myotherfile yetanotherfile ...
>>
>> And yet...
>>
>>> c:\cygwin\bin\echo $PATH
>> $PATH
>>
>> What the heck is going on? Are there any rules here at all? Sorry if I'm
>> missing something dumb. And sorry for apologizing for it. And......
>
>In this case, the Cygwin DLL intercedes and handles quoting for the Cygwin 
>app that
>you invoked (echo).  But it only does quoting.  You're mixing the notion of 
>quoting with
>environment handling.  They are two different things.

Does "handles quoting" mean that it implements the "Quoting" section, and only that section, of the bash manpage?  I just need to know exactly what it does.  It clearly does not *only* do quoting.  That's why I demonstrated the asterisk example.  It is doing at least wildcard expansion in addition to quoting.  What else is it doing?  I'm trying to figure this out so I know how to properly escape or quote a general command in order to execute it from a Windows application without any unexpected changes.

Thanks for the response,
Jesse



      

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