Declared in rt_sys.h, the
_sys_istty() function determines whether a file handle is attached to an interactive device.
The ARM libraries call
determine whether a file handle (that is being used for an output file stream) is attached
to an interactive device.
For file streams that are attached to interactive devices, the ARM library:
- Provides unbuffered behavior by default, in the absence of a call to
- Prohibits seeking.
stderr, are interactive devices, but are line-buffered at program startup.
The return value is one of the following values:
fhis not attached to an interactive device.
fhis attached to an interactive device.
- An error occurred.