5 POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/isatty.html}
9 Portability problems fixed by Gnulib:
12 This function is declared in a different header file (namely, @code{<io.h>})
16 On native Windows, this function also returns true for character devices such
19 On native Windows, this function returns false for Cygwin consoles.
21 This function crashes when invoked with invalid arguments on some platforms:
25 Portability problems not fixed by Gnulib: