Commonly used commands for monitoring log files in Linux!

A log file is a record file or a collection of files used to record system operation events, and can be divided into event logs and message logs. For system administrators, log files are very important. They record the system's operating status and error information, etc., and can help us find and solve problems in time. So how to monitor log files in a Linux system? The following is an introduction to the specific content.

　1. Use the tail command to monitor log files in real time

The tail command is great for viewing the content at the end of a file, especially when monitoring log files. Simply enter the command to display the last few lines of the file in real time, providing the convenience of viewing real-time information.

tail -f /path/to/logfile

In this command, /path/to/logfile represents the location of the log file you want to monitor. After executing this command, tail will continue to display the end content of the log file and refresh in real time to display the latest information.

　2. Use less command to view log files and track

less command is a powerful text viewer, often used to browse file contents. You can easily view and browse the contents of log files by entering specific commands.

　less /path/to/logfile

After viewing the log file in less, use the Shift F shortcut key to enable trace mode. In this mode, less will automatically refresh the log content and display the latest information.

　3. Use grep command to filter specific log information

　The grep command can be used to find specific patterns in text. We can use grep to filter log files and only display the information we care about. Example:

tail -f /path/to/logfile | grep “keyword”

　Among them, keyword is the keyword you want to filter. After using this command, tail will output the contents of the log file in real time, and only display those lines containing keywords.

　4. Use the journalctl command to view the system log

In some Linux distributions, you can use the journalctl command to view system logs. This command can display various log information of the system, including startup information, output of system services, and various other system events. Examples are as follows:

　journalctl -f

After using this command, journalctl will output the contents of the system log in real time and will continuously refresh it.

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