Re: /dev/tty01 will not open on Beaglebone Black

[RVP <rvp%SDF.ORG@localhost>]

On Wed, 30 Aug 2023, Brook Milligan wrote:

> I am trying to communicate with uart4 on a Beaglebone Black, but cannot open /dev/tty01; open(2) just hangs.
>
> [...]
> #ls -l /dev/tty01
> crw-------  1 uucp  wheel  12, 1 Apr 11 12:20 /dev/tty01
>
> However, when run by root, the following code just hangs, i.e., the open() never returns.
>
> 	#include <fcntl.h>
> 	int main ()
> 	{
> 	  int fd;
> 	  char const* filename = "/dev/tty01";
> 	  fd = open(filename,O_RDWR);
> 	}

If you open a dial-in device without O_NONBLOCK, then open() won't return until
the carrier is asserted. Does Ctrl-C (or kill -9) end the program?

-RVP