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The System log typically contains the greatest deal of information by default about your Linux system. It is located at /var/log/syslog, and may contain information other logs do not. You should consult the System Log when you can't locate the desired log information in another log.
System Log Sample:
Jan 6 06:35:01 pizza1 CRON[29271]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
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