Some components are broken in raw tty

[harrison314]

Information

• OS: CentOs (minimal, without GUI)
• Version: 7
• Terminal: tty (raw terminal in VirtualBox, HyperV)

Describe the bug Some components (in my case Rule and Confirm) is broken.

To Reproduce Access the terminal (without Putty or SSH) directly on the linux console. It manifested itself in VirtualBox, HyperV and a physical computer.

Example program to reproduce:

        Console.WriteLine("Encoding : {0}", AnsiConsole.Console.Profile.Encoding);
        Console.WriteLine("Height : {0}", AnsiConsole.Console.Profile.Height);
        Console.WriteLine("Width : {0}", AnsiConsole.Console.Profile.Width);
        Console.WriteLine("Unicode : {0}", AnsiConsole.Console.Profile.Capabilities.Unicode);
        Console.WriteLine("Ansi : {0}", AnsiConsole.Console.Profile.Capabilities.Ansi);
        Console.WriteLine("IsTerminal : {0}", AnsiConsole.Console.Profile.Out.IsTerminal);
        Console.WriteLine("Legacy : {0}", AnsiConsole.Console.Profile.Capabilities.Legacy);
        Console.WriteLine("Links : {0}", AnsiConsole.Console.Profile.Capabilities.Links);

        Console.WriteLine();
        Console.WriteLine();

        Console.WriteLine("AnsiConsole.Write(new Rule());");
        AnsiConsole.Write(new Rule());

        Console.WriteLine();
        Console.WriteLine();

        Console.WriteLine(@"AnsiConsole.Confirm(""Is this prompt OK?"", true);");

       _ = AnsiConsole.Confirm("Is this prompt OK?", true);

Screenshots

Problem with Confirm:

Sometimes there is also a problem with Rule:

Context Workaround for AnsiConsole.Confirm:

new ConfirmationPrompt("Is this prompt OK? [lime][[y/n]] (y)[/]")
        {
            DefaultValue = true,
            ShowChoices = false,
            ShowDefaultValue = false
        }
        .Show(AnsiConsole.Console);

If I use the blue text color, the output is broken as well.

---

Please upvote :+1: this issue if you are interested in it.

[nils-a]

@harrison314 what do you mean by "raw tty"? Are you talking about the virtual console, or do you have a real physical Teletype Terminal hooked up to your system?

[harrison314]

what do you mean by "raw tty"? Are you talking about the virtual console, or do you have a real physical Teletype Terminal hooked up to your system?

virtual console

[nils-a]

I think I found... "something"

Can you please show me the output of locale, showconsolefont and tput colors? Also, can you try to run your sample program with the NO_COLOR environment variable set?

[harrison314]

locale:

LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

showconsolefont:

tput colors:

8

When using NO_COLOR, the problem did not appear.

[nils-a]

So there are two things going on here:

unicode support

We're determining whether unicode is supported, or not, by "asking" the .NET framework: If the output encoding contains the word unicode, then we're assuming unicode is enabled. The .NET framework, in turn, uses one of LC_ALL, LC_MESSAGES, or LANG and parses the encoding from there.

Whether unicode is really working, has nothing to do with it. Also, keep in mind that the virtual console does never really support unicode, but rather it supports a 255 character wide window of the selected console font. In my tests, unicode in the virtual console was broken more often than not.

I am fairly certain, your error displaying the Rule goes back to whether the unicode characters used to display it are currently working on the console, or not. (Try playing with unicode_start/unicode_stop and the consolefont in use, but I didn't have much luck of getting a consistent result.)

color support

The terminfo-db contains a value of 8 colors for a $TERM of linux. In contrast, we fall back to 256 colors for linux systems. One could call this a bug. However, I feel, the number of terminals that are in use currently and not supporting at least 256 colors is rather limited.

I would suggest setting NO_COLOR to disable the colors completely.

[harrison314]

Is it not possible to solve at least the display of colors at the Spectre.Console level?

Or provide a code snippet, how to use NO_COLOR automatically in C# code?

[nils-a]

Well, you can always set the environment variables using System.Environment.SetEnvironmentVariable:

System.Environment.SetEnvironmentVariable("NO_COLOR", "1", System.EnvironmentVariableTarget.Process);

However, if you can (and are willing to) modify the code of the program, you could also set the number of colors manually:

AnsiConsole.Profile.Capabilities.ColorSystem = ColorSystem.Legacy;

[borrrden]

For a bit of further context here, this same behavior for Rule happens when piping output to Out-File on Powershell 7.4.5 on Windows. The weird thing is it does NOT happen when redirecting via > but only with | Out-File or | Out-String.

It also, unfortunately, happens when adding 2>&1 to the command line invocation and then redirecting to a file.