[daemon.log]Every daemon without a separate facility logs to
daemon.log. The priority of log events is not relevent.[debug]File
debug has messages useful for debugging.The priority of log events are
not relevent.[dmesg] After the kernel has booted, all kernel messages
are written to dmesg for later reference.This file is not rotated and
only exists for a single boot cycle before being overwritten.Note that
the choice of the name is a little unfortunate, as the dmesg command
prints the current kernel log ring buffer,which is continuously
updated and new kernel events are logged.These messages are written to
kern.log; The dmesg file is not modified until the next restart of the
system.[kern.log] Log messages with the kern facility end up in this
file.The contents are mostly what the kernel spits out,after being
formatted by klogd.[lpr.log]Log messages with the lpr facility end up
in this file.
[mail.log] Log entries related to the mail system(using the mail
facility) go into this file. For easier parsing by scripts,mail log
entries are also written to mail.info, mail.warn,and
mail.err,according to their priority. Unfortunately,Debian's default
MTA,exim4, does not use this file.[messages]Pretty much everything
that is not an error or a trivial log entry,and not related to
authentication,daemons ,cron(or other automatic schedulers),mail,and
news goes here.
btmp auth.log syslog boot
btmp shows a log of the file /var/log/btmp, which contains all the bad
login attempts. auth.log receives log entries related to
authentication,and other events that are critical to privacy or
security issues. everything not related to authentication end up in
syslog file. syslog is the catch-all log file on a debian system.
log messages produced during the initialization sequence will be
logged to boot.