[Operating system basics] What files are usually in the /var/log/ folder in Linux? What is the role of separation?

In Linux systems, the /var/log/ folder usually contains system log files that record various activities and events of the system for administrators to troubleshoot and monitor.

Here are some of the files commonly found in the /var/log/ folder and what they mean:

1. auth.log: Record information related to system authentication and authorization, such as user login, sudo commands, etc.

2. kern.log: Record kernel-related information, such as system startup, hardware failure, etc.

3. syslog: Record various events and messages of the system, including the start and stop of system services, error messages of applications, etc.

4. messages: Record various messages and warnings of the system, including kernel messages, system service messages, etc.

5. dmesg: Record kernel messages when the system starts, including hardware detection, driver loading, etc.

6. boot.log: Record various information during system startup, including errors and warnings during startup.

7. lastlog: Records information such as the time and IP address of the user's last login.

8. wtmp: Record the login and logout information of all users in the system.

These log files are very important for system administrators, they can help them understand the operation of the system, find and solve problems in time.

In addition to the common log files mentioned above, the /var/log/ folder may contain other log files, depending on the configuration and usage of the system. Here are some other possible log files and their meanings:

1. cron: Record the execution of scheduled tasks.

2. maillog: Record the operation of the mail server and the status of mail transmission.

3. secure: Record system security-related information, such as SSH login, firewall rules, etc.

4. audit: Record system audit logs, including user and process activities, file access, etc.

5. httpd: Record the access log and error log of the web server.

6. cups: Record printer usage and error messages.

7. samba: Record the usage and error information of the Samba file sharing server.

In short, the /var/log/ folder in the Linux system contains a large number of log files, which record various activities and events of the system, which are very important for system administrators. Administrators can learn about the running status of the system by viewing these log files, find and solve problems in time, and ensure the stability and security of the system.