[SOLVED] How to detect the configured codepage of my console (Linux)?

[Hartmut]

Normally consoles on Linux use UTF8-codepage, but sometimes I use a GNOME-console which is configured to use good old DOS-codepage (CP850).
My question is: is it possible for a running FPC console program to detect the codepage, which is configured in the console, from where the program was started?

I tried already:
   writeln('DefaultSystemCodePage=', DefaultSystemCodePage);
   writeln('Console codepage: ', GetTextCodePage(OUTPUT));
but in both consoles they show '0'.

I use FPC 3.2.0. Thanks in advance.

[MarkMLl]

The best I can suggest for the moment is looking at the LANG shell variable, which at least in the case of KDE's Konsole has a codepage appended.

I don't know the extent to which a desktop environment terminal session has locale etc. information distinct from that of X11, or to what extent that is distinct from an internal kernel setting.

MarkMLl

[tetrastes]

I tried already:
   writeln('DefaultSystemCodePage=', DefaultSystemCodePage);
   writeln('Console codepage: ', GetTextCodePage(OUTPUT));
but in both consoles they show '0'.

Add uses cwstring (see https://wiki.freepascal.org/FPC_Unicode_support#DefaultSystemCodePage).

[MarkMLl]

Add uses cwstring (see https://wiki.freepascal.org/FPC_Unicode_support#DefaultSystemCodePage).

Good point. I thought Lazarus did that automatically under some circumstances?

MarkMLl

[Bart]

Add uses cwstring (see https://wiki.freepascal.org/FPC_Unicode_support#DefaultSystemCodePage).

Good point. I thought Lazarus did that automatically under some circumstances?

MarkMLl

If you use LazUtf8 unit (as the LCL does), it will.

Bart

[Hartmut]

The best I can suggest for the moment is looking at the LANG shell variable, which at least in the case of KDE's Konsole has a codepage appended.

Thanks MarkMLl for that suggestion. Unfortunately the LANG shell variable in both consoles contains
   LANG=de_DE.UTF-8
so there is no difference.

Add uses cwstring (see https://wiki.freepascal.org/FPC_Unicode_support#DefaultSystemCodePage).

Thanks tetrastes for that idea. Unfortunately this changes
   writeln('DefaultSystemCodePage=', DefaultSystemCodePage);
   writeln('Console codepage: ', GetTextCodePage(OUTPUT));
in both consoles to 65001. Maybe because with unit cwstring the currently set LANG environment variable is asked, as your documentation link says. The LC_CTYPE environment variable is not defined in both consoles.

Any other ideas?

[MarkMLl]

I'm not particularly comfortable with this since not being able to get at something as important as the codepage has always struck me as incredibly sloppy design.

The fact that you're talking about the Gnome console suggests that you're talking about a shell session wrapped in a graphical window (i.e. the canonical xterm etc.)... however even starting there I can't find anything other than some woolly references to $LANG, $LC_TYPE and the locale. Does  locale charmap  show anything useful?

Gut feeling is that you need an escape sequence etc. which is fed through the pty to whatever GUI component (xterm etc.) is handling the rendering i.e. using Cairo or whatever. So far I've not turned up anything useful, but there /might/ turn out to be some sort of X11 backdoor similar to what a window manager etc. can use to query font metrics.

MarkMLl

[KodeZwerg]

Sorry to jump unprepared in, just my 2ct on this topic, how to detect = i do not know, but i think linux goes same like windows, when no codepage can be resolved an oem codepage like cp850 for western europe will be used. This is just a guessing in the dark!

[Thaddy]

type "export" in a console. The configuration can be used in Tprocess and parsed. or:

Code: Pascal  [Select][+][-]

1. function GetActiveCodepage: string;
2. begin
3.   result := GetEnvironmentVariable('LC_ALL');
4.   if result= '' then
5.     result:= GetEnvironmentVariable('LC_CTYPE') else
6.   if result= '' then
7.     result:= GetEnvironmentVariable('LANG') else
8.   if result= '' then
9.     result := GetEnvironmentVariable('LANGUAGE') else
10.   if result = '' then
11.     result:= GetEnvironmentVariable('LC_MESSAGES') else
12.   if result= '' then
13.     result:= 'UTF-8'; // by no means fool proof
14. end;

[MarkMLl]

type "export" in a console. The configuration can be used in Tprocess and parsed.

Shell variables can be used directly, and I think we've already exhausted that approach.

MarkMLl

[Thaddy]

Ok, Mark... I added a function to my reply... Find the fool....

Or simply use Tprocess and call locale -a

[Hartmut]

Does  locale charmap  show anything useful?

Command "locale charmap" shows in both consoles "UTF-8", so there is no difference.

type "export" in a console. The configuration can be used in Tprocess and parsed.

Thank you Thaddy. There are some differences. As a workaround I could use them, if we don't find a better (more directly) way.

Code: Pascal  [Select][+][-]

1. function GetActiveCodepage: string;
2. begin
3.   result := GetEnvironmentVariable('LC_ALL');
4.   if result= '' then
5.     result:= GetEnvironmentVariable('LC_CTYPE') else
6.   if result= '' then
7.     result:= GetEnvironmentVariable('LANG') else
8.   if result= '' then
9.     result := GetEnvironmentVariable('LANGUAGE') else
10.   if result = '' then
11.     result:= GetEnvironmentVariable('LC_MESSAGES') else
12.   if result= '' then
13.     result:= 'UTF-8'; // by no means fool proof
14. end;

Unfortunately all this environment variables either contain the same or do not exist in both consoles.

[Thaddy]

II am aware of that. Alas I had to write "by no means fool proof"

[Hartmut]

Or simply use Tprocess and call locale -a

Command "locale -a" returns the same result in both consoles.

[MarkMLl]

...do not exist in both consoles.

If it's the same distro and version that might be your best bet.

Output some characters, take a screenshot, OCR it :-)

MarkMLl