Last updated on: 2019-12-20
Authored by: Rackspace Community
This article identifies what is in each of the Linux® logs, where they are stored, and which distributions (distro) use the logs.
For most of the following logs, you can use vi
, less
, tail
, or cat
to view the log details. Exceptions to this rule are noted in the descriptions.
/var/log/alternatives.log (Ubuntu® operating system/Debian® (DEB))
Stores information from update-alternatives
.
/var/log/apache2/access.log (Ubuntu operating system/DEB)
Stores requests, such as HTTP GET
and POST
requests, that are processed
by Apache®. Parse these logs by using log parsers such as awstats
or
webalizer
. Configure this log by using the CustomLog
directive.
/var/log/apache2/error.log (Ubuntu operating system/DEB)
Stores all Apache errors and diagnostic information found while serving
requests. The location of the error.log file is set by the ErrorLog
directive.
/var/log/audit/audit.log
Stores information from the Linux audit daemon (auditd
). This log contains
information about the files on which users perform reads or writes. For example,
you can use this log to determine who changed a specific file.
/var/log/auth.log
Contains system authorization information, including user logins and which authentication mechanism was used.
/var/log/boot
Contains information about the boot process after the kernel is loaded. Information includes things such as system file checks, mounting a file system, starting a firewall, starting network devices, and starting services.
/var/log/btmp
Contains failed login attempts. Use the last
command to view this log.
For example: last -f /var/log/btmp |more
/var/log/cron
Stores information from crondaemon
and anacron
after they start a cron
job.
/var/log/dmesg
Contains kernel information about hardware and devices detected during the boot process. This file is overwritten when new messages are sent to it, such as during the next boot.
/var/log/dpkg.log (Ubuntu operating system/DEB)
Stores information that is logged when a package is installed or removed by
using the dpkg
command.
/var/log/faillog
Contains failed user login attempts. Use faillog
to access the information.
/var/log/kern.log (Ubuntu operating system/DEB, and can be configured for Centos® and Red Hat®)
Contains log details from the kernel’s initialization at system bootup, as well as any kernel errors or informational messages that are sent from the kernel.
/var/log/lastlog
Displays recent login information. Run this command to view the log entries.
/var/log/maillog.log (Centos/Red Hat)
Stores information from the mail server that is running on your system, such as Sendmail® logging information.
/var/log/mail.log (Ubuntu operating system/DEB)
Stores information from the mail server that is running on your system, similar to maillog.log for the Centos and Red Hat flavors.
/var/log/mail
Contains additional logs provided by your mail server. For example: Sendmail stores collected mail statistics in /var/log/mail/statistics.
/var/log/messages (Centos/Red Hat)
Contains global system messages, including the messages logged during boot.
Log entries include information from mail
, cron
, daemon
, kern
, auth
,
and so on.
/var/log/sa
Contains daily sar
files collected by the sysstat
package.
/var/log/samba/
Contains log information stored by the samba
daemon, which is used to
connect to Microsoft® Windows® and Linux file systems.
/var/log/setroubleshoot/
Used by SELinux to capture security issues in files and log that information.
/var/log/secure (Centos/Red Hat)
Stores information related to authentication and authorization privileges.
For example, sshd
logs all information here, including unsuccessful attempts.
var/log/wtmp or /var/log/utmp
Contains login records and shows who is logged into the system. The who
command uses this file to display the information.
/var/log/yum.log (Centos/Red Hat)
Stores information that is logged when a package is installed or removed.
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