Re: -displayfd outputting some garbage?

[Jon Turney <jon.turney@dronecode.org.uk>]

On 08/02/2017 01:02, Matt D. wrote:
> On 2/7/2017 7:46 PM, Matt D. wrote:
>> I have an xinit script which outputs the display id to a file with the
>> following option:
>>
>> xinit .. -displayfd 3 3>$HOME/.display

Thanks for reporting this.

For future issues, can I ask you to use the cygwin list, per [1]

[1] https://cygwin.com/ml/cygwin-xfree-announce/2015-03/msg00001.html

I hope you mean ' xinit -- -displayfd 3 3>$HOME/.display'

>> This outputs correctly '0' but appends 0x00 and 0x0A. Why is it
>> outputting a null byte and this 0x0A?

Yeah, this seem to be a bug in xinit (which needs to insert itself into 
the displayfd pipeline to learn the display number for it's own purposes)

$ X -displayfd 3 3>~/.display
[...]
$ xxd ~/.display
00000000: 300a                                     0.

$ xinit -- -displayfd 3 3>~/.display
[...]
$ xxd ~/.display
00000000: 3000 0a                                  0..

> This is causing issues where I try to perform:
>
> echo $(cat .display)
>
> Which results in:
>
> bash: warning: command substitution: ignored null byte in input
> 0

This warning is new in bash 4.4, I think.

I think this is a just a warning though, and shouldn't actually cause 
any issues?

-- 
Jon Turney
Volunteer Cygwin/X X Server maintainer

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