[Octave-bug-tracker] [bug #56651] "warning: unable to open X11 DISPLAY" is raised on start when DISPLAY is not set

[Mike Miller]

URL:
  <https://savannah.gnu.org/bugs/?56651>

                 Summary: "warning: unable to open X11 DISPLAY" is raised on
start when DISPLAY is not set
                 Project: GNU Octave
            Submitted by: mtmiller
            Submitted on: Sat 20 Jul 2019 07:42:28 PM PDT
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: Confirmed
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

The warning message "warning: unable to open X11 DISPLAY" is now raised by
Octave when the interpreter first starts, when the DISPLAY variable is not
set. This warning is unnecessary information, in particular when the user just
wants to run Octave for number crunching and does not need any graphical
capabilities. This is a regression introduced recently in commit 596312d4f25d
(https://hg.savannah.gnu.org/hgweb/octave/rev/596312d4f25d), which deals with
how the display_info class is initialized.

Example _correct_ behavior in Octave 3.8.2 through 5.1.0:


$ unset DISPLAY
$ octave --eval 1
octave: X11 DISPLAY environment variable not set
octave: disabling GUI features
ans =  1
$ octave --quiet --eval 1
ans =  1
$ octave-cli --eval 1
ans =  1


New behavior since 596312d4f25d:


$ unset DISPLAY
$ octave --eval 1
octave: X11 DISPLAY environment variable not set
octave: disabling GUI features
warning: unable to open X11 DISPLAY
ans =  1
$ octave --quiet --eval 1
warning: unable to open X11 DISPLAY
ans =  1
$ octave-cli --eval 1
warning: unable to open X11 DISPLAY
ans =  1


As you can see this warning is now raised in all three scenarios, where it was
not at all before. The 'octave' wrapper program does print its own information
about DISPLAY not being set, which I think is appropriate, and can be silenced
easily with '--quiet'.

This was detected by https://gitlab.com/mtmiller/octave-test-suite (see the
log at https://gitlab.com/mtmiller/octave-test-suite/-/jobs/255845834), which
is my attempt at an automated daily external test suite to catch regressions
with how Octave behaves from the command line, for example.




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