isastream man page


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

isastream — test a file descriptor (STREAMS)


#include <stropts.h>

int isastream(int fildes);


The isastream() function shall test whether fildes, an open file descriptor, is associated with a STREAMS-based file.

Return Value

Upon successful completion, isastream() shall return 1 if fildes refers to a STREAMS-based file and 0 if not. Otherwise, isastream() shall return -1 and set errno to indicate the error.


The isastream() function shall fail if:

The fildes argument is not a valid open file descriptor.

The following sections are informative.

Future Directions

The isastream() function may be removed in a future version.

See Also

The Base Definitions volume of POSIX.1‐2008, <stropts.h>


2013 IEEE/The Open Group POSIX Programmer's Manual