linux log file usage summary

Use the log file summary

• / var / log / cron:
  your crontab schedule has not actually been carried out? The process has no errors occur? Your / etc / crontab if written correctly? In this query the log file to see.
  
  
• / var / log / dmesg:
  Record system the core information generated by the detection process at startup. Because CentOS by default when you start the core hardware detection process to cancel the display, so the extra copy of the data recorded in the file;
  
  
• / var / log / lastlog:
  can record information about when the system is above all the most recent account login system. lastlog command is the use of recording information of the file to be displayed.
  
  
• / var / log / maillog or / var / log / mail / * :
  Record the message exchanges of information, it is mainly recorded sendmail (SMTP protocol provider) (provided by the POP3 protocol) and dovecot information generated by it. SMTP is the protocol used by the sender, POP3 is the protocol used by receivers. dovecot is sendmail and software are two sets of communication to reach agreement. 
  
  
• var / log / messages /:
  This file is very important, error messages (or important information) almost occurred in the system will be recorded in this file; error inexplicable event of a system, the file is sure to review the Log Files one.
  
  
• / var / log / secure:
  Basically, as long as the involved "need to enter the account password" software, then when landing (landing regardless of right or wrong) will be recorded in this file. The system comprises a login program, gdm login program used by the graphics interface, su, sudo and other procedures, as well as network connection ssh, telnet and other procedures, login information will be described here;
  
  
• / var / log / wtmp, / var / log / faillog:
  These two documents can record the correct landing system's account information (wtmp) account information (faillog) landing and error used! last is to read wtmp to display, which track usage behavior for the general account's helpful!
  
  
• / var / log / httpd / * , / var / log / news / *, / var / log / samba / *:
  different network services will use their own login file to record all the information generated by their own! Within the above directory is the individual service developed by the log file.