Xref: utzoo comp.lang.c:15268 comp.unix.wizards:13904
Path: utzoo!utgpu!attcan!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Re: printf, data presentation
Keywords: printf, terminals, fixed format screens
Message-ID: <808@auspex.UUCP>
Date: 6 Jan 89 18:22:37 GMT
References: <19@xenlink.UUCP> <731@picuxa.UUCP> <8332@ihlpl.ATT.COM> <444@marob.MASA.COM>
Reply-To: guy@auspex.UUCP (Guy Harris)
Followup-To: comp.unix.wizards
Organization: Auspex Systems, Santa Clara
Lines: 26

>If I understand your need, the fcntl VMIN and VTIM parameters

"ioctl(TCSETA)" and company, not "fcntl".

>may help.  If you set VMIN=0 and VTIM>0, read() returns immediately
>if characters are available, or in VTIM 10th-secs if the queue is dry.

This works on UNIXes that have VMIN and VTIME (S3, S5, SunOS 4.0, some
others).  It doesn't work on older UNIXes, or non-UNIX systems; I think
he wanted a routine that would, on all (or, at least, most) systems, do
what was appropriate on that system (whether UNIX or not).

>I use VMIN=0,VTIM=1 to grab the next char, or return immediately if
>none is available.

Try VTIME=0 instead (although this may not work under S3); that will
return immediately, rather than after 1/10 second (which VTIME=1 does).

>>Even a blocking version (that would return a char once typed,
>>without waiting for a newline) would be useful.
>
>Try reading with VMIN=1,VTIM=0.  This is akin to the Berkeley CBREAK mode.

Actually, the equivalent of turning on V7 CBREAK (not Berkeley - they
didn't invent CBREAK, AT&T did) is turning ICANON off and setting VMIN
to 1 and VTIME to 0.  VMIN and VTIME are meaningful only if ICANON is off.