The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group


isatty - test for a terminal device


#include <unistd.h>

int isatty(int fildes);


The isatty() function tests whether fildes, an open file descriptor, is associated with a terminal device.


The isatty() function returns 1 if fildes is associated with a terminal; otherwise it returns 0 and may set errno to indicate the error.


The isatty() function may fail if:
The fildes argument is not a valid open file descriptor.
The fildes argument is not associated with a terminal.




The isatty() function does not necessarily indicate that a human being is available for interaction via fildes. It is quite possible that non-terminal devices are connected to the communications line.






Derived from Issue 1 of the SVID.

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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