Check if an elf executable is running with GUI or CUI on UNIX

Question

In Windows you can check if IMAGE_OPTIONAL_HEADERS.Subsystem from the PE header is equal to either IMAGE_SUBSYSTEM_WIN_GUI or IMAGE_SUBSYSTEM_WIN_CUI.

Is there a UNIX/ELF equivalent?

I've checked

https://en.wikipedia.org/wiki/Executable_and_Linkable_Format#File_header

along with general Google and

http://linux.die.net/man/5/elf

a few times but I haven't found anything.

Answer 1

Is there a UNIX/ELF equivalent?

No. UNIX has no concept of a GUI or CUI Subsystem, so the question "what subsystem does this executable use?" is completely meaningless.