Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!seismo!sundc!pitstop!sun!amdcad!ames!mailrus!cwjcc!tut.cis.ohio-state.edu!osu-cis!dsacg1!dsacg3!vfm6066
From: vfm6066@dsacg3.UUCP (John A. Ebersold)
Newsgroups: comp.lang.c
Subject: Re: input ready under UNIX ??!!??
Keywords: input, unix, help
Message-ID: <1122@dsacg3.UUCP>
Date: 28 Oct 88 14:06:38 GMT
Article-I.D.: dsacg3.1122
References: <771@necis.UUCP> <12430@steinmetz.ge.com>
Reply-To: vfm6066@dsacg3.UUCP (John A. Ebersold)
Organization: Defense Logistics Agency Systems Automation Center, Columbus
Lines: 23

Several years ago, on a PDP-11 under Ultrix-11 I did basically the following:
(Forgive the pigdin C :-)  ).

	long l;

	fp = fopen(the tty);
	fd = fileno(fp);

	if (ioctl(fd, FIONREAD, &l) != -1)
		if (l > 0)
			printf("There are characters\n");

I believe this is a Berkeleyism - the flavor I am not sure of.

There is also fcntl:

	fcntl(fd, FNDELAY, arg);
To quote the manual:

"nonblocking I/O; if no data is available to a read call, or if a write
operation would block, the call returns -1 with the error EWOULDBLOCK."

Also a Berkeleyism.