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logger – Log the Corresponding Entry in the Syslog

The logger command is used to add messages to the system log, which is also known as the syslog. It is a useful tool for system administrators who need to keep track of various system events, such as system startups, shutdowns, and other system-related activities.

Overview

The logger command is used to add messages to the system log, which can be accessed using the syslog command. The syntax for the logger command is as follows:

logger [options] [message]

Here, the options are used to modify the behavior of the logger command, while the message is the text that will be added to the system log. If no message is specified, then the logger command will read from standard input.

Examples

logger "System shutdown initiated"

The above command will add the message “System shutdown initiated” to the system log.

echo "System startup initiated" | logger

The above command will read the message “System startup initiated” from standard input and add it to the system log.

logger -p user.info "User login successful"

The above command will add the message “User login successful” to the system log with the priority set to “user.info”.

Options

Here are the available options for the logger command:

Option Description
-p, --priority Sets the priority of the message. The priority can be specified using the facility.level notation, where facility is one of the following: user, local0, local1, local2, local3, local4, local5, local6, local7. The level can be one of the following: emerg, alert, crit, err, warning, notice, info, debug.
-t, --tag Sets the tag for the message. By default, the tag is set to the name of the command that was used to add the message to the system log.
-u, --socket Sends the message to the specified socket instead of the default /dev/log.
-s, --stderr Sends the message to standard error instead of the system log.
-h, --help Displays the help message and exits.
-v, --version Displays the version information and exits.

Troubleshooting Tips

If you are having trouble adding messages to the system log using the logger command, here are some troubleshooting tips:

  • Ensure that the syslog daemon is running on your system.
  • Check the permissions of the /dev/log socket. The user running the logger command must have write access to this socket.
  • Verify that the message is being added to the correct facility and level. Use the -p option to set the priority of the message.

Notes

  • The logger command is typically used in shell scripts to add messages to the system log.
  • The system log can be viewed using the syslog command or by examining the contents of the /var/log/syslog file.

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