On Tue, 23 Dec 2008 17:56:00 -0500 (EST) "Robert P. J. Day" <rpjday@xxxxxxxxxxxxxx> wrote: > i'm well aware of the use of the pseudo tty ports under /dev/pts, > but i never understood the value of having a distinct "devpts" > filesystem, until today. > > i was working with an embedded system with a flashed root filesystem > that included /dev so, obviously, everything under /dev was also read > only. i installed dropbear for an ssh server, but every attempt to > ssh to that system failed. Ssh (or actually any login kind of program) wants to chown/chmod the controlling tty, which is of course not possible on a RO filesystem. > after tracing the operation of dropbear, i tracked it down to the > fact that dropbear was trying to open a pseudo-port corresponding to > the connection and was, of course, failing since all of /dev was > read-only. > > after i mounted /dev/pts (rw), ssh connections started to work. is > this why /dev/pts was developed? to work around RO /dev directories? > or was there some other reason? No, that's just coincidence. The main reason is that in the old days the number of PTYs were limited (to 256, IIRC) so you could only have a limited number of remote sessions and xterms on your machine. /dev/pts removed that limit. Erik -- Erik Mouw -- mouw@xxxxxxxxxxxx GPG key fingerprint: D6AC 7F15 A26E C5C4 62E0 4A58 FCF9 551C 9B48 B68D
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