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Re: PATHEXT is fundamental to Windows and Should be recognised by CYGWIN
On 8/8/2016 10:33 AM, Corinna Vinschen wrote:
> On Aug 8 09:43, cyg Simple wrote:
>> As for PATHEXT we can do the following scenario instead.
>> export PATHEXT="$PATHEXT;.TXT"
>> vi foo.txt
>> :set ff=dos
>> cmd /c foo
> As you show here, the PATHEXT definition is so that it also contains
> file suffixes which require to know the interpreters starting them. To
> implement that, the lib would have to either read the registry to know
> the connection between suffix and interpreter (which is pretty
> convoluted), or it would have to "start the file", aka call ShellExecute
> on the file, without knowing what process will come up as child process.
> In your example that would be Notepad or Write.
> The way this works is just not feasible to be used from inside the DLL,
> - ShellExecute does not return a handle to the called process, so the
> parent can't wait(2) for it.
> - ShellExecute does not allow to specify an environment for the child
> process. Cygwin's Windows environment is reduced to minimal size.
> Cygwin children inherit the POSIX environment by a simple copy
> process. Only when starting a non-Cygwin process, this process gets
> a full Windows environment by means of the matching CreateProcess
Sorry, it seems I confused the issue. I was suggesting with this
example that as a Cygwin shell user I could use this technique to start
a file if I so choose without any modification to Cygwin.
> So, if we actually implement PATHEXT, its usage would be limited to
> suffixes of binary files and files starting with #!<interpreter>, or we
> would have to use a way to start an application which doesn't work well
> in a POSIX scenario, or we would have to search the registry for the
> suffix linkage. Additionally to searching a variable number of files
> for each single file access.
I tried "chmod +x foo.txt; ./foo.txt" but that results in Cygwin
assuming the text file is a script and executing each line of the file.
If PATHEXT were used only to determine that the file should be passed to
ShellExecute instead it might be beneficial but since I can easily just
do "cmd /c foo.txt" then probably not so much.
> Additionally I would (again?) like to stress that PATHEXT is a feature
> of CMD, aka, the shell. It's not a feature of the underlying libs.
And other application type programs and libraries. WSH for one makes
use of PATHEXT.
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