@node isatty
@subsection @code{isatty}
@findex isatty

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/functions/isatty.html}

Gnulib module: isatty
@mindex isatty

Portability problems fixed by Gnulib:
@itemize
@item
This function is declared in a different header file (namely, @code{<io.h>})
on some platforms:
MSVC 14.
@item
On native Windows, this function also returns true for character devices such
as @file{NUL}.
@item
On native Windows, this function returns false for Cygwin consoles.
@item
This function crashes when invoked with invalid arguments on some platforms:
MSVC 14.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@end itemize
