Question on BSD Pseudo-TTY ioctl's (slave vs. master)

William J. Bogstad wjb at cogsci.cog.jhu.edu
Sat Oct 6 11:42:26 AEST 1990


	I'm trying to port a 4.3BSD program (window(1))to SUN OS 4.0.3 and
am having a minor problem with code that deals with pseudo-ttys.  The code
attempts to change the slave side terminals settings of the pseudo-tty by
doing the same ioctl's on the master side.  I currently open the slave set
the terminal settings and then close it.  Unfortunately, after closing the
PTY the terminal settings get reset to the defaults.  The USENIX 4.3BSD
manual pages for PTYs list the master side ioctl's, but don't say whether or
not the slave side ioctl's are supposed to work on either side.  I would
assume that 4.2BSD does work that way, but I would like to know if that is
just accidental or an intended capability.  Is there any way do this other
then opening (and keeping open) the slave side?  A "portable" solution would
be preferred.  I would also be curious about how other UNIX systems that
implement PTYs deal with this question.

				Thanks,
				Bill Bogstad



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