Syslogd Linux and Unix Command

The system-log daemon coordinates messages about a Linux-based computer

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Linux supports a rich ecosystem of software that records core system activities. One of these, syslogd, runs as a system daemon. It records certain system events and kernel messages to a file.

Nowadays, syslogd is obsolescent, with most modern Linux distributions relying on different software to log this information.

How the System Log Works

system log

A system log stores messages from applications and core OS subroutines. Common components include:

  • Application: Individual programs send diagnostic messages. A system logger can track the location of these message files.
  • Hardware: Information specific to the hardware of the machine.
  • Security: Events that log potential security problems, or daemons that focus on system security and stability.
  • System: Information related to the Linux kernel.

The logger runs in the background, through a daemon.

How to Interact with Logs

logger tool in linux

Because syslogd is a daemon, you don't interact with it directly. Instead, use other tools.

To see log messages in memory, use dmesg. To manually insert an entry into the system log, use the logger command. Use your distribution's log-display tool to view a consolidated list of log records, or find the individual log file and examine it directly. For example, the system log is usually at /var/log/syslog. In fact, most logs are in the /var/log directory, although some applications store their log files with their own binaries.