System Messages

UNIX has a strict policy of reporting error messages.

Error messages of interactive commands are sent to the terminal screen,

Non-interactive commands ``log'' messages to files in the directory /var/log/.

Log files

A log file is a plain text file.

The main log files are: syslog , boot.msg , messages
They contain kernel messages. boot messages and messages from some primary services.

Services with large log files have their own log file, for example, sendmail: /var/log/maillog.

Example:

   tail -f /var/log/syslog
 
>tail -f /var/log/messages

Nov  2 11:46:26 lucas kernel: eth0: transmit timed out, tx_status 00 status e000.
Nov  2 11:46:26 lucas kernel:   diagnostics: net 0e80 media 4810 dma ffffffff.
Nov  2 11:49:50 lucas su: (to root) felix on /dev/pts/0
Nov  2 11:49:50 lucas su: pam_unix2: session started for user root, service su