Provided by: manpages-posix-dev_2017a-2_all 
PROLOG
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.
NAME
isastream — test a file descriptor (STREAMS)
SYNOPSIS
#include <stropts.h>
int isastream(int fildes);
DESCRIPTION
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.
ERRORS
The isastream() function shall fail if:
EBADF The fildes argument is not a valid open file descriptor.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
The isastream() function may be removed in a future version.
SEE ALSO
The Base Definitions volume of POSIX.1‐2017, <stropts.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original
IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced
during the conversion of the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .