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Special Forums IP Networking Message passing from child to parent using pipes Post 302858073 by Don Cragun on Saturday 28th of September 2013 12:49:06 PM
Old 09-28-2013
Your statement of requirements and your code snippets do not seem to be related to each other at all. You talk about reading data from a user, but there is absolutely nothing in your while loop that reads any data. You talk about the functions doEcho() and doDayTime(), but there are no definitions for these functions and no calls to these functions. You talk about network programming and you talk about half-duplex pipes, but there are no pipes and you aren't showing us how your socket is set up. You have a doprocessing() function that each child process calls, but, again, there is no declaration for this function.

With all of the missing declarations, missing functions, missing context, I'm not going to try to recreate and debug your program. By visual inspection, it still looks to me like the parent will fork() as many children as it can until the system is saturated or the system starts failing fork()s due to user process count limits.

With all of this confusion and missing details, I have no idea how to help you. The only thing I can suggest is to go back to your online tutorial and seek help from the people who maintain that tutorial; maybe they will have the needed context to understand what you're trying to do.
 

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TALK(1) 						    BSD General Commands Manual 						   TALK(1)

NAME
talk -- talk to another user SYNOPSIS
talk person [ttyname] DESCRIPTION
The talk utility is a visual communication program which copies lines from your terminal to that of another user. Options available: person If you wish to talk to someone on your own machine, then person is just the person's login name. If you wish to talk to a user on another host, then person is of the form 'user@host' or 'host!user' or 'host:user'. ttyname If you wish to talk to a user who is logged in more than once, the ttyname argument may be used to indicate the appropriate terminal name, where ttyname is of the form 'ttyXX'. When first called, talk sends the message Message from TalkDaemon@his_machine... talk: connection requested by your_name@your_machine. talk: respond with: talk your_name@your_machine to the user you wish to talk to. At this point, the recipient of the message should reply by typing talk your_name@your_machine It does not matter from which machine the recipient replies, as long as his login-name is the same. Once communication is established, the two parties may type simultaneously, with their output appearing in separate windows. Typing control-L '^L' will cause the screen to be reprinted. Typing control-D '^D' will clear both parts of your screen to be cleared, while the control-D character will be sent to the remote side (and just displayed by this talk client). Your erase, kill, and word kill characters will behave normally. To exit, just type your interrupt character; talk then moves the cursor to the bottom of the screen and restores the terminal to its previous state. Permission to talk may be denied or granted by use of the mesg(1) command. At the outset talking is allowed. CONFIGURATION
The talk utility relies on the talkd system daemon. See talkd(8) for information about enabling talkd. FILES
/etc/hosts to find the recipient's machine /var/run/utmpx to find the recipient's tty SEE ALSO
mail(1), mesg(1), wall(1), who(1), write(1), talkd(8) HISTORY
The talk command appeared in 4.2BSD. In FreeBSD 5.3, the default behaviour of talk was changed to treat local-to-local talk requests as originating and terminating at localhost. Before this change, it was required that the hostname (as per gethostname(3)) resolved to a valid IPv4 address (via gethostbyname(3)), making talk unsuitable for use in configurations where talkd(8) was bound to the loopback interface (normally for security reasons). BUGS
The version of talk released with 4.3BSD uses a protocol that is incompatible with the protocol used in the version released with 4.2BSD. Multibyte characters are not recognized. BSD
August 21, 2008 BSD
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