Linux log files location and how do I view logs files?

Almost all logfiles are located under /var/log directory (and subdirectory). You can change to this directory using cd command but you need to be the root user. You can use less, more, cat or tail command to see the logs.

Go to /var/logs directory:# cd /var/logs


View common log file /var/log/messages using any one of the following command:# tail -f /var/log/messages
# less /var/log/messages
# more -f /var/log/messages
# vi /var/log/messages

Output:

Jul 17 22:04:25 router dnsprobe[276]: dns query failed
Jul 17 22:04:29 router last message repeated 2 times
Jul 17 22:04:29 router dnsprobe[276]: Primary DNS server Is Down... Switching To Secondary DNS server
Jul 17 22:05:08 router dnsprobe[276]: Switching Back To Primary DNS server
Jul 17 22:26:11 debian -- MARK --
Jul 17 22:46:11 debian -- MARK --
Jul 17 22:47:36 router -- MARK --
Jul 17 22:47:36 router dnsprobe[276]: dns query failed
Jul 17 22:47:38 debian kernel: rtc: lost some interrupts at 1024Hz.
Jun 17 22:47:39 debian kernel: IN=eth0 OUT= MAC=00:0f:ea:91:04:07:00:08:5c:00:00:01:08:00 SRC=61.4.218.24 DST=192.168.1.100 LEN=60 TOS=0x00 PREC=0x00 TTL=46 ID=21599 DF PROTO=TCP SPT=59297 DPT=22 WINDOW=5840 RES=0x00 SYN URGP=0