How to view logs in Linux system (common commands)

cat

tail -f

Log file description

 
 /var/log/Message The information and error log after system startup is one of the most commonly used logs in Red Hat Linux 
 
 /var/log/secure Security-related log information 
 
 /var/log/Maillog Log information related to mail 
 
 /var/log/cron Log information related to scheduled tasks 
 
 /var/log/spooler Log information related to UUCP and news devices
 
 /var/log/boot.log Daemon Start and Stop Related Log Messages

 System:
 
 # uname -a # View Kernel /OS/CPU information
 
# cat /etc/issue 
 
 # cat /etc/redhat-release # View operating system version 
 
 # cat /proc/cpuinfo # View CPU information 
 
 # hostname # View computer name
 
 # lspci -tv # List all PCI devices
 
 # lsusb -tv # List all USB devices
 
 # lsmod # Listing loaded kernel modules 
 
 # env # Viewing environment variables 

 Resources:
 
 # free -m # View Memory usage and swap usage 
 
 # df -h # View partition usage 
 
 # du -sh <directory name> # View the size of the specified directory
 < # grep MemTotal /proc/meminfo # View memory total 
 
 # grep MemFree /proc/meminfo # View free memory 
 
 # uptime # View system running time, number of users, load 
 
 # cat /proc/loadavg # View system load

 Disks and partitions:
 
 # mount |
  Column -t # View the mounted partition status 
 
 # fdisk -l # View all partitions 
 
 # swapon -s # View all swap partitions 
 
 # hdparm -i /Dev/hda # View disk parameters (only for IDE devices) 
 
 #dmesg |
  Grep IDE # View IDE device detection status at startup 

 Network: 
 
 # ifconfig # View all network interface properties 
 
 # iptables -L # View firewall settings 
 
 # route -n # View routing table 
 
 # netstat -lntp # View all listening ports 
 
 # netstat -antp # View all established Connections 
 
 #netstat -s # View Network Statistics 

 Process: 
 
 # ps -ef # View all processes
 
 # top # Real-time display of process status (detailed in another article) 

 User: 
 
 # w # View event User 
 
 # id <username> # View specified user information
 
 # last # View user login log
 
 #cut -d: -f1 /etc/passwd # View all users of the system
 
 #cut -d: -f1 /etc/group # View all groups in the system
 
 # crontab -l # View the current user's scheduled tasks

 
 Service:
 
 # chkconfig –list # List all System Services 
 
 # chkconfig –list |
  Grep on # List all started system services 

 Programs:
 
 # rpm -qa # View all installed packages

 
 Original link: http://mushme.iteye.com/blog/1001478