Re: Windowless Perl

[Brian Inglis <Brian.Inglis@SystematicSw.ab.ca>]

On 2019-06-18 12:15, Jon Turney wrote:
> On 18/06/2019 16:27, Andrey Repin wrote:
>>> On 2019/06/10 13:12, Chris Wagner wrote:
>>>> I didn't know about run, thanks for the tip. However when I use it to 
>>>> launch something from the Start Menu Run command, it still pops open a 
>>>> terminal window of some kind for a fraction of a second.  I'm on
>>>> Windows 7.
>>> Windows has a flag set in each EXE as to whether or not it is a console 
>>> or GUI program.  There are tools that can set the flag in a given EXE 
>>> file.
>> It's not a flag, it's an exported function.
>> If a program exports winmain(), it's a gui program, if it exports main(),
>> it's a console program.
> No. It really is a flag.

Strictly speaking a field flag value:

$ objdump -x $(dirname $(cygpath $COMSPEC))/csrss | grep -w '^Subsystem'
Subsystem               00000001        (NT native)
$ objdump -x /setup | grep -w '^Subsystem'
Subsystem               00000002        (Windows GUI)
$ objdump -x /bin/cygwin1.dll | grep -w '^Subsystem'
Subsystem               00000003        (Windows CUI)

> See
> https://docs.microsoft.com/en-us/windows/desktop/debug/pe-format#windows-subsystem
> You are describing the behaviour of (recent versions of) the Microsoft linker,
> which guesses the default value of this flag based on what symbols are defined
> See
> https://docs.microsoft.com/en-us/cpp/build/reference/entry-entry-point-symbol,
> specifically the sentence "If the /DLL or /SUBSYSTEM option is not specified,
> the linker selects a subsystem and entry point depending on whether main or
> WinMain is defined."

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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