README

January 21, 2015 ยท View on GitHub

pty version 4.0, February 9, 1992. Copyright (c) 1992, Daniel J. Bernstein. All rights reserved.

  1. Read WTF if you want to know what all these files are for.
  2. Run SYSCONF. Check the bottom of README for any notes relevant to your system.
  3. Make and run CHECKCONF. Edit config/* if necessary. If you don't have privileges, make sure to change config/ptybin.h, config/ptydir.h, and config/sess*.h. If you make any changes to config/*.h, you may want to make and run CHECKCONF again. (If you don't have privileges, you may also want to change flagxonlysecure = 0 to flagxonlysecure = -1 in ptymain.c line 36; this will eliminate a warning message each time you use pty.)
  4. Make.
  5. Make INSTALL. (This doesn't actually install pty; it only makes the INSTALL program, which you run in step 7.)
  6. If you have privileges, and you don't have a tty group (group 4), make one.
  7. If you have privileges, and you want to run pty as its own uid rather than root, make a pty uid.
  8. As root, run INSTALL, or ``INSTALL root'' if pty should run as root. If you don't have privileges, run INSTALL anyway, and don't worry about the error messages. Tricks: yes skip | ./INSTALL to see all the steps of installation without executing any; yes ok | ./INSTALL to do complete installation without having to confirm each step.
  9. Change /dev/tty* to be owned by pty if (1) pty isn't running as root but (2) you still want to take advantage of pty's security features. (If you want, you can chown only some of the ttys---tty[t-z], say. Then pty will stick to those. In this case you should probably edit config/ptyext.h to match.) Also change /dev/pty to be owner pty and mode 0600 if you want to prevent denial of service attacks; keep in mind that this will stop valid non-root programs from opening ttys, and that it will not close the dozens of other denial of service attacks on your machine. (You may want to chmod and chown only a few of the ptys, to keep them free for pty just in case.)
  10. If you want, invoke wtmprotate, sessrotate, or sclogrotate from your daily, weekly, or monthly cron scripts. (wtmprotate may already be handled by your vendor's scripts.) Also invoke utmpinit, sessnowinit, and scnowinit from /etc/rc.local. Don't worry about these if you don't have privileges.
  11. Run checkptys. If you want, arrange to have checkptys run periodically by cron.
  12. If you want to make sure that pty works, look through TESTS and see whether your setup works the same way.
  13. Fill out FORMLETTER and send it to me.

Thanks to Scott Schwartz for his extensive comments; Paul Graham for utmpinit and for bug reports; Eliot Moss for all his work with pty 3.0, much of which inspired changes in pty 4.0; Maarten Litmaath for mtty; Seth Robertson for all his help; Keith Waclena for some incisive comments on pty 3.0's configuration scripts; Larry McVoy for admitting he was wrong about POSIX; Kartik Subbarao and Icarus Sparry for testing; and the cast of thousands for feature requests and suggestions. Thanks also to Dave Curry for checking pty's security.

Probably the best documentation to start with is SESS.draft2. Then try pty-basic.1, then pty.1, then pty-opts.1. pty can do a lot of stuff--- don't expect to absorb it all at once.

pty is known to work in at least one configuration on each of the following machines:

Sun 4/280, SunOS 4.0.3 note that because of an OS bug (fixed in SunOS 4.1), pty -t will fail from non-job-control shells (like sh) unless pty runs as root Sun 4/490, SunOS 4.1.1 tested by KS Sun 3/160, SunOS 4.1.1 thanks to Seth Robertson Sun 3/50, SunOS 4.1.1 Sun SLC, SunOS 4.1.1 tested by IS VAX 8600, BSD 4.3+NFS (Mt. Xinu) DECStation 5400, Ultrix 4.1 (Rev. 52) must add -YPOSIX -DPOSIX to CC in Makefile DECStation 5820, Ultrix 4.1 (Rev. 200) must add -YPOSIX -DPOSIX to CC in Makefile

Other notes for the future:

Convex UNIX 9.0 must add -pcc -DPASS8=0 -DEXTB=15 to CC in Makefile; fd passing has a very weird bug, need to look at it in depth BSD 4.4 seems to work with the new fd passing system, but the machine crashes; various CSRG/BSD folks are trying to find the kernel bug SVR4 three people working on the port AIX two people working on the port IRIS (which?) must add -D_BSD_COMPAT -DIRIS_UGH_PTYS to CC in Makefile; must add -lbsd to PTYLIBS in Makefile; must define TTY_TERMIO in config/ttyopts.h; must define SYSV in config/sysv.h

``Bizarre uses for pty... My favorite is: pty -0 jive | pty fn. Fn is the client for a networked chat system. The result is a killer. :-)'' ---Sean Casey