[SOLVED] Linux: How to detect whether STDOUT was redirected?

[Hartmut]

I want a function which tells me, whether STDOUT of my console program was redirected or not like
   myprogram > outfile

In http://forum.lazarus.freepascal.org/index.php/topic,41936.0.html there is a solution for Windows, but I need it for Linux (Ubuntu 18.04). Can somebody help?

I'm an absolute beginner on Linux, so please be not to short in your answer. Thanks a lot in advance.

[mpv]

You can check stdout is a terminal using isatty() function. If not then stdout is redirected

[Hartmut]

That sounds interesting. But I don't find this function, in which unit is it?
http://www.math.uni-leipzig.de/pool/tuts/FreePascal/units/node12.html#SECTION0012369000000000000000
says it is in unit "Linux", but I still get a compilation error: Identifier not found "IsATTY"

Thanks for your help.

[alex256]

Code: Pascal  [Select]

1. uses
2.     termio;
3.  

[Thaddy]

Code: Pascal  [Select]

1. {$ifdef fpc}{$mode delphi}{$H+}{$endif}
2. uses termio;
3. begin
4. writeln(IsATTY(output));
5. end.

[Thaddy]

Alex , posts crossed.

[Hartmut]

It works! Thanks a lot to all who helped me.