How to Use the logger Command in Linux
Understanding the logger Command in Linux
The logger command is a powerful tool for adding messages to the system log, specifically to the syslog file, usually located at /var/log/syslog. It’s an essential utility for system administrators and developers who need to log messages programmatically.
Basic Usage
To log a simple message to syslog, you can use the following command:
logger messageThis will record “message” in the syslog with the default settings.
Logging from Standard Input
You can also pipe input directly into logger. This is particularly useful when you want to log the output of commands or scripts:
echo log_entry | loggerLogging to a Remote Syslog Server
If you need to send logs to a remote syslog server, you can specify the server’s hostname and port. By default, syslog uses port 514. Here’s how you can do it:
echo log_entry | logger [-n|--server] hostname [-P|--port] portThis command will direct the log entry to the designated server instead of the local machine.
Customizing Tags
By default, the logger command uses the logged-in user’s name as the tag for each log entry. However, you can specify a custom tag to make your logs more identifiable:
echo log_entry | logger [-t|--tag] tagThis can help in categorizing logs into different applications or scripts easily.
Setting Log Message Priorities
Each log message can be assigned a priority level, which determines its importance. The default priority is user.notice. You can set a different priority by using the -p or --priority flag:
echo log_entry | logger [-p|--priority] user.warningTo see a full list of priority options, refer to the manual page by running man logger.
Conclusion
The logger command is a versatile tool that enhances logging capabilities on Linux systems. Whether you are logging simple messages or directing logs to remote servers, this command provides the necessary flexibility. For more detailed information, you can check the official manual at GNU logger Manual. Happy logging!