Linux Journal: Linux's Tell-Tale Heart, Part 1
Jun 27, 2000, 07:37 (0 Talkback[s])
(Other stories by Marcel Gagné)
Re-Imagining Linux Platforms to Meet the Needs of Cloud Service Providers
"Today's column marks the beginning of a new series, where we
dig deep within the heart of your Linux system and listen.
Whether you know it or not, your Linux system is constantly
talking to you in a kind of system monologue, or diary, keeping you
abreast of everything in its life. All you need to do is pay
attention. Sometimes the information will look like idle
chit-chat. Sometimes, the health of your system depends on it."
"As time goes on and you get more comfortable with your Linux
system, you've no doubt realized just how powerful it really is.
There's a lot going on under the hood, and a lot of feedback is
being generated from all that information. Today, I'm going to show
you how some of this information is generated, how you can
customize it, and how you can be in several places at once!..."
"A good deal of the logs your system generates come to you
courtesy of the syslogd dæmon. The syslogd dæmon is a
program that runs in the background, independent of whatever else
you may do on your system, but it does pay attention. That's its
job; to collect information on what is going on and reporting it.
Actually, this is as good a place as any for a definition. For
those of you who may not already know this, my description of
syslogd is actually a pretty good definition of what a dæmon
is, at least the first part. By definition, a dæmon is a
program which, after being spawned (either at boot or by a command
from a shell), disconnects itself from the terminal that started it
and runs in the background. If you then disconnect from the
terminal session that started the program or log out entirely, the
program continues to run in the background. What it does there is a
function of what the dæmon is for. The inetd dæmon
listens for network connections, while syslogd watches, monitors