brian@bucc2.UUCP (10/15/87)
> /* ---------- "Three-way write" ---------- */ > Hi! > > I'm looking for C source code to a three (or more) way write program. > Does something like this exist?? > I am currently writing such a program. It will only run on SysV, though, since I am using shared memory. ............................................................................... { bucs1!brian Brian Michael Wendt {uiucdcs,cepu,ihnp4}!bradley! { brian { bucc2!brian
karl@ddsw1.UUCP (Karl Denninger) (10/19/87)
In article <15100001@bucc2> brian@bucc2.UUCP writes: > >> /* ---------- "Three-way write" ---------- */ >> I'm looking for C source code to a three (or more) way write program. >> Does something like this exist?? > I am currently writing such a program. It will only run on SysV, though, >since I am using shared memory. I've posted a up-to 15 user chat program for System III and later (it uses named pipes) to alt.sources a while ago. It's written for System V, and would have to be hacked for other systems, but should be pretty close... Anyone who needs it, feel free to mail. If I get enough interest I will consider a repost of the current version. -- Karl Denninger UUCP : ...ihnp4!ddsw1!karl Macro Computer Solutions Dial : +1 (312) 566-8909 (300-1200) "Quality solutions at a fair price" Voice: +1 (312) 566-8910 (24 hrs)
mpl@sfsup.UUCP (M.P.Lindner) (10/22/87)
In article <273@ddsw1.UUCP>, karl@ddsw1.UUCP writes: > In article <15100001@bucc2> brian@bucc2.UUCP writes: > >> I'm looking for C source code to a three (or more) way write program. > >> Does something like this exist?? > > I am currently writing such a program. It will only run on SysV, though, > >since I am using shared memory. > > I've posted a up-to 15 user chat program for System III and later (it uses > named pipes) to alt.sources a while ago. It's written for System V, and > would have to be hacked for other systems, but should be pretty close... Has anyone ever considered writing a "write" program that writes to ttys? Amazingly enough, this is how the two way "write" program does it, and guess what? It's portable! I know there are certain drawbacks, like each user must know all the other users in the conversation, but guess what? It's portable. Sorry to sound facetious, but I'm sick of porting little programs like "this does a cat backwards, and uses semaphores." Peace. Mike Lindner attunix!mpl
brad@bradley.UUCP (10/26/87)
why not have the program sent through comp.sources.unix?
brian@bucc2.UUCP (10/27/87)
> /* Written 5:06 pm Oct 21, 1987 by sfsup.UUCP!mpl in bucc2:comp.unix.ques */ > Has anyone ever considered writing a "write" program that writes to ttys? > Amazingly enough, this is how the two way "write" program does it, and guess > what? It's portable! I know there are certain drawbacks, like each user ^^^^^^^^^^^^^^^^^ > must know all the other users in the conversation, but guess what? It's > portable. > > Sorry to sound facetious, but I'm sick of porting little programs like "this > does a cat backwards, and uses semaphores." Peace. > > Mike Lindner > attunix!mpl > /* End of text from bucc2:comp.unix.ques */ You sure are right there are certain drawbacks! In order to make the wonderful, standard, portable write command work everyone on the system has permission to write to your tty. Consider the implications of that. Novices troublemakers can have fun by doing things like cat a.out > /dev/tty101, and worse. People who know what they are doing can send wonderful control sequences to your terminal. Wonderful control sequences that will make the system think _you_ typed whatever _they_ want it to think. Like rm -r * ............................................................................... I heard it on the grep-vine... { bucs1!brian Brian Michael Wendt {uiucdcs,cepu,ihnp4}!bradley! { brian { bucc2!brian
allbery@ncoast.UUCP (10/28/87)
As quoted from <2241@sfsup.UUCP> by mpl@sfsup.UUCP (M.P.Lindner): +--------------- | In article <273@ddsw1.UUCP>, karl@ddsw1.UUCP writes: | > In article <15100001@bucc2> brian@bucc2.UUCP writes: | > >> I'm looking for C source code to a three (or more) way write program. | > > I am currently writing such a program. It will only run on SysV, though, | > >since I am using shared memory. | > I've posted a up-to 15 user chat program for System III and later (it uses | > named pipes) to alt.sources a while ago. It's written for System V, and | | Has anyone ever considered writing a "write" program that writes to ttys? | Amazingly enough, this is how the two way "write" program does it, and guess | what? It's portable! I know there are certain drawbacks, like each user +--------------- The purpose of the IPC is to prevent the output of three different users all being jumbled together; think of it as a "write spooler", that's basically the idea. Since there is no way to write to a tty "atomically" (try it! --and no, O_APPEND doesn't work on character devices), this is the only way to "spool" tty writes. -- Brandon S. Allbery necntc!ncoast!allbery@harvard.harvard.edu {{harvard,mit-eddie}!necntc,well!hoptoad,sun!mandrill!hal}!ncoast!allbery "Uncle _who_?" -- Lt. Worf