Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site utah-cs.UUCP Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!zehntel!hplabs!hao!seismo!utah-cs!donn From: donn@utah-cs.UUCP (Donn Seeley) Newsgroups: net.bugs,net.unix Subject: Why 4BSD 'stty' uses stdout instead of stdin Message-ID: <2993@utah-cs.UUCP> Date: Mon, 13-Aug-84 19:26:43 EDT Article-I.D.: utah-cs.2993 Posted: Mon Aug 13 19:26:43 1984 Date-Received: Wed, 15-Aug-84 06:35:49 EDT References: <895@trwrb.UUCP> <1228@dalcs.UUCP> <747@dual.UUCP> <46@rlgvax.UUCP> <318@wucs.UUCP> <5024@utcsrgv.UUCP> <2540@mit-eddie.UUCP> Organization: University of Utah CS Dept Lines: 30 From Guy Harris (guy@rlgvax.UUCP): The USG UNIX solution is, I think, better; the USG "stty" command acts on its standard *input*. There is a reason for the curious behavior of the Berkeley 'stty', as I'm sure Guy knows, and it's probably useful to mention it in passing. On 4BSD (and V7?) a tty must be opened for writing in order for a process to set the tty's modes. This does make a certain amount of sense; if you don't want someone to write on your tty, then you usually don't want them to set your tty's mode either. It was decided that it was simpler to get and set modes on the same descriptor, hence the output to stderr and so on. I'm not sure how USG Unix handles this: does the tty merely have to be writable, as opposed to being opened for writing? Does 'stty' get modes from stdin and set them on stdout? Does it care how the descriptor was obtained? The second of these alternatives (get stdin, set stdout) would work on 4BSD... If there was a '-c' option for copying modes, you could perhaps say 'stty -c < /dev/ttyz1 > /dev/ttyz2' and copy the modes from one tty to another. 'stty -g' sounds useful, except that the output of 'stty' is already so close to being input to 'stty' that it's a pity (ouch) it wasn't extended a little farther so that 'stty < /dev/ttyz1 > file; stty `cat file` > /dev/ttyz2' could work. More wishful thinking, Donn Seeley University of Utah CS Dept donn@utah-cs.arpa 40 46' 6"N 111 50' 34"W (801) 581-5668 decvax!utah-cs!donn