Introduction to syslogd
terminal 1:
terminal 2:
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syslog daemon
responsible from syslog. This structure collects all messages from
running programs to the logs. It categorizes all of messages
according to its types and priority, and presents to us. This is very
useful for error debugging. We can use this messages to find the
actual problem if we have any one at any time. Actually I used that
in my previous post. You may wanna see it.
Reading Logs
Now, let's look at
how we can read logs. FHS determines the location of logs as
/var/log. We can use tail command to read last ten messages like
that:
cd /var/log
tail messages #
note: if you don't see anything or get no file error type: tail
syslog
output of this
command:
As you can see
from last ten messages, at 10:42:24 I disconnected the modem I cut
the internet, which is a message from network manager and it have
saved into syslog.
Following Logs from tail
A system
administrator would use tail -f command to follow log messages like
that:
tail -f
/var/log/messages or tail -f /var/log/syslog
Because by using
-f parameter with tail command, we can read new messages from running
programs at right now. This is very handful for debugging. Also,
almost all system manager executes that command in another terminal
all the time, to see the messages coming through when the programs
are running.
Let's see how it
works: I entered the command to read syslog continuously, and I
disabled eth0 in another terminal, the terminal views are given
below:
terminal 2:
As you can see
from terminal 2, message says eth1 disabled when we type and entered
ifconfig eth1 down into other terminal. It works :).
If you have
any question or need some help about system logs in linux, leave a
comment below.