por Do you know what they are and how log analysis occurs? Logs are detailed records of events and activities that occur in a computer system., such as a server, application, or device. These logs include information about errors, warnings, actions taken by users, system accesses, and other relevant events.
Let’s see what log analysis in Linux consists of.
Log analysis
The log system, which in Spanish means record, is a standard mechanism that is responsible for collecting messages generated by programs, applications and daemons.. Each message consists of the source (the program or application that generated it), priority, date, and time.
The main logs that we can find within the system are:
/var /log /kern.log: keeps a log of kernel messages.
/var /log /syslog: log of messages from the system and its programs.
/var /log /dmesg– System boot information and connections hardware mostly.
/var /log /debug: program debugging information.
/var /log /Xorg.0.log: information about the graphical environment.
/var /log /boot.log: boot information.
/var /log /fontconfig.log: system font configuration.
/var /log /mail.log: mail server logs.
/var /log /auth.log: connections to the system, including failed attempts and accesses such as root.
/var /log /crond: scheduled tasks (cron).
/var /log /daemon.logs: specific alerts for some daemons.
/var /log /errors.log: It shows us errors.
/var /log /httpd: If we have an Apache server, the events are logged here.
/var /log /messages.log: general system alerts.
/var /log /mysqld.log: MySQL event log.
We see, for example, that not all logs are found, but for log analysis some important ones are found, such as the kernel.
Now we will delve into some of these for log analysis.
/var /log /kern.log
This file contains information about kernel events, such as error messages, warnings, system information, and activity logs. To view the contents of this file in the Linux terminal, you can use the command cat /var/log/kern.log. You can also use a text editor such as «nano» or «vim» to view and edit the file. Let us remember that you need to have permissions root to execute these activities and do log analysis within this log.
/var /log /syslog
It is a file that logs system messages and running applications. It is the main system log, which contains a wide variety of information, including errors, warnings, system events, debugging messages, and more.
This file The system and applications are continually updated, so it can grow quickly and take up a significant amount of disk space. With it you can do log analysis.
/var /log /dmesg
This file contains messages from the operating system kernel, which have been generated during system boot and stored in the kernel buffer. These messages provide information about the devices hardware detected and configured during boot, as well as any errors or warnings that occurred during the boot process.
/var /log /debug
The /var/log/debug subdirectory used to store system debugging logs. These logs are generated by programs and services running on the system and may contain detailed information about errors, warnings, and other conditions that can affect the operation of the system.
/var /log /Xorg.0.log
The Xorg.0.log file is a log file generated by the Xorg server on Linux, used to display information related to starting, configuring, and using the X server.
The /var/log/ directory is the directory where log files are stored on most Linux distributions, including Ubuntu, Debian, Fedora, CentOS, etc. The Xorg.0.log file is located in this directory and, thanks to it, log analysis can be performed.
/var /log /boot.log
Contains information about the system boot process. This file logs kernel messages, system service actions, and system boot events.
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