Date: Tue, 7 Dec 1999 06:10:51 +0100 (CET)
From: "[ISO-8859-1] Jörg Ziefle" <joerg.ziefle@studbox.uni-stuttgart.de>
To: weave@eng.umd.edu
Subject: linux_logo solution: using FIFOs instead of cron

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Hi Vince,

your linux_logo is nice, but the system configuration is improvable:

**********************************************************************
Why not use FIFOs for the issue files instead of using cron for having
up-to-date greeting files?
**********************************************************************

Here's my solution (with a bit of Perl, you can do it also in C(++), if
you like):

* The logo "daemon":
---------------BEGIN
#!/usr/bin/perl

chdir; # go home
$FIFO = $ARGV[0];
$PROGRAM = $ARGV[1];
$ENV{PATH} .= ":/etc"; # could be made generalized

while (1) {
  unless (-p $FIFO) {
    unlink $FIFO;
    system('mknod', $FIFO, 'p') && die "can't mknod $FIFO: $!";
  }

  # next line blocks until there's a reader
  open (FIFO, "> $FIFO") || die "can't write $FIFO: $!";
  print FIFO `$PROGRAM`;
  close FIFO;
  sleep 2;    # to avoid dup signals
}
---------------END

* My /sbin/init.d/boot.local (SuSE System) includes the following lines:

/home/joerg/bin/logo /etc/issue /home/joerg/bin/issue &
/home/joerg/bin/logo /etc/issue.net /home/joerg/bin/issue.net &

* And finally, the "shell scripts" /home/joerg/bin/issue:

/usr/local/bin/linux_logo -F "Welcome to #H!\n#O Version #V, Compiled
#C\n#N #M#X#T Processor#S, #R RAM, #B Bogomips Total\n#L\n#U\n"

and /home/joerg/bin/issue.net:


/usr/local/bin/linux_logo -F "Welcome to #H!\n#O Version #V, Compiled
#C\n#N #M#X#T Processor#S, #R RAM, #B Bogomips Total\n#L\n#U\n"

(You have to fix the word wrap made by the MUA.)

All files have to be set executable.
This way, I get an up-to-date issue file every time I log in and can
easily add things to be shown (e.g. a fortune or a random tip).

The drawback of this is, if the logo daemon dies, nobody can't log
in any more, so you should perhaps write a small script that checks every
5 minutes or so the existence of the logo daemon and starts it if
necessary.

I hope this could help and I am excited to hear from you about this
solution.

Regards,

Jörg