If you like to code in Perl then you didn't need me to list this :-)

eh, ya still have to call your Perl script from rc.shutdown

http://search.cpan.org/~rhandom/Net-...Net/Server.pod

FWIW, can run from inetd

can use various protocol(s)

send message to command line. If KDE have rcv then likely work here too.

http://search.cpan.org/search?query=...+user&mode=all

--
Alan.

"remote" (FWIW) turned up more hits for me than "lan" or "net" :-) :-)

FreeBSD's shutdown has a switch that makes it notify "remote" users.

http://lists.kde.org/?l=kde-nonlinux...0863816991&w=2

http://www.linuxquestions.org/questi...r-on-x-636283/

http://www.google.com/linux?q=shutdo...rch&hl=en&sa=2

--
Alan.

The thing is wall is based on broadcasting to all users on a host - not broadcasting to all hosts on a Lan. Ok - so my idea wasn't particularly secure but it was just something to get the OP going with an experimental "homegrown" solution i.e. a way to get started using easily available tools. It was in no way meant to be a finished product. Sorry if I offended anyone

The requirement got me searching for "ready made" solutions and none was forthcoming - in fact I found more solutions for Windows networks. To me it would seem quite a common requirement and I was surprised there didn't seem to be a ready made product. This got me thinking about the common tools available in a Linux environment - netcat was the first thing that sprang to mind as the "Swiss army knife for TCP/IP" as it is commonly known. The fact that it supports UDP subnet broadcasts seemed ideal.

IP Messenger
This is a pop up style LAN Messenger for multi platforms.
It is based on TCP/IP(UDP).
It does not require server machine.
Simple, lightweight, and compact size.

UNIX
X11R6 XIP Messenger by candy (97/09/14)

GNOME/GTK+ Gnome IP Messenger by T.Matsumaru (99/09/29)

GNOME2 IP Messenger by T.Kato (2008/10/27)
Java
Now, Java version is only open to public in Japanese Page

This still sounds like the thing woddsman is looking for -it's also available for win/mac. The GTK version is very old (uses gtk-1.2) and was very hard to find and then only in Japanese, but i got tuxdev to translate the bits of text for me. If you want it I look here around for it, if the X version is too ugly, or the Gnome version has too many depends...

Following the link to the java version:
http://www.ipmsg.org/index.html.ja
I found some other related stuff, including a perl version an emacs version, a text version, jave and java swt versions.

Ooo, boy, talk about a sparse web page. No screen shots, no online docs, nothing. Not to mention the app is in GTK, which I prefer to avoid.

Perl is a foreign language to me.

Oof! That thread is from the year 2001!

True, and that is where rwall enters the picture. rwall will intercept messages broadcast across a LAN and then use wall to relay the message locally. There also is rwho, which can reveal all current login sessions across the LAN. Seems rwall could send messages in a shotgun approach --- to everything everywhere, or the information from rwho could be used to send a LAN broadcast message only to certain users.

You did not offend me. Offering ideas is how solutions are found. People might not agree with each specific idea, but such conversations act as a catalyst toward finding a palatable solution a person seeks. Not to mention I learned something new about netcat. Thanks for helping!

Bingo. There is no ready-made solution. Seems odd to me too, especially considering Unix is 40 years old and Linux systems are almost 20. As I mentioned previously, the shutdown command displays a shutdown message, but the design is limited to the mainframe way of connecting users, not the modern way of using a LAN. That is, the broadcast message is local to the server and not to the LAN.

I don't read Japanese. Also, seems Java might be a tad heavy for a simple messaging system. The KDE popup I receive from a wall message is crude but functional. Nonetheless, thanks for finding the links!

I think the rwalld and rwhod tools probably provide the basics of what I was seeking originally.

One caveat I noticed after posting yesterday. When I exited X/KDE, there were a slew of messages appearing suddenly in tty1, which is where I logged in and started X/KDE. Apparently those test messages I had sent on my LAN went to tty1 in addition to my Konsole terminal and KDE popup and other machines on the LAN. No damage done, but sloppy. As of yet, I don't see a way to fine tune the process except by using rwho to pinpoint where messages should be sent. I don't know whether I can further limit to which tty the message is sent.

I also have not yet figured out how to get rwalld in Slackware to work with /etc/netgroup. I don't know whether the problem is my not understanding syntax correctly, or the version provided with Slackware does not support the -n option.

To anybody interested, I did get rwall running and the KDE (3.5.10) write daemon provides an ugly but functional popup.

I never could get the rwall daemon to run from within inetd, so I start /usr/sbin/rpc.rwalld from rc.local.

To automate the messages I want to send from within shell scripts I use the following syntax:

echo "message" | rwall $HOSTNAME

Where $HOSTNAME is the host name of the box to which I want the message seen. As my office machine is my primary work horse here, the messages I want to send always go there. I run a basic sanity check with a single ping to ensure the office machine is running before trying to send a message through rwall.

Do know that rpc.rwalld must be running on both machines. Also that rwall depends upon wall, so start any testing first with wall. The basic syntax to test wall is similar to rwall:

echo "message" | wall

Interestingly, as noted by the discussion within this thread, seems system messaging is indeed something that has received little attention the past several years with Linux-based systems. I found the following web page that highlighted that deficiency and future plans:

Features/System Wide Desktop Notification

Seems the future should provide better support for receiving system messages on graphical desktops, but that day is not today.

In my original post I asked whether Xfce has any tools equivalent to the KDE write daemon. I found two:

notification-daemon-xfce
xfce4-notifyd

If I understand correctly, the first app is no longer supported or maintained. Also, I think both tools only support messaging through d-bus. I don't know whether either tool will intercept messages through (r)wall. Perhaps somebody more familiar with Xfce can expand upon that topic.

I really don't understand the need for you to have everyone on your network know that a machine has been turned off but I suppose that's your business. For stuff like this most people would use something like snmp. You could have the box that is shutting down send an snmp trap to an smnp trap daemon and this could be logged, emailed, transmitted to other hosts, etc. I think the reason why this kind of stuff may have existed in Windows is because of netbeui or whatever that protocol is. From what I remember it is not a routeable protocol so it only exists within a broadcast domain. I believe this is what is used when hosts in a broadcast domain in Windows advertise workgroups and that sort of thing. It seems like you are looking for an easy solution to a problem that not many other people have or care about so maybe you need to create this program/daemon thing yourself.