Top :
Top Command can provide the top processes, CPU Load, Memory Utilization, Swap Utilization
Running/Zombie Process, Uptime, etc..
iostat:
This command will provide the information about the disk utilization, Read/Write rate, etc..
vmstat:
vmstat command provides the swap memory utilization report
sar (System Activity Reporter)
sar tool can provide the report about CPU Load, iowait and other useful info at specified intervals.
dmesg
dmesg command displays all the server errors including Hardware, booting, network errors
This command will retrieve the information from log files which located in /var/log
Other Useful commands to collect some info about the server :
runlevel - To Know the Current Run Level
netstat –a - To see the Network sessions
netstat –rn - To View the gateways configured
who / finger - To View the Users logged in detail
ps –ef - To view all the running process and its related files
sestatus - To check SELINUX status
service iptables status - To check firewall status
ifconfig –a - To View the Network cards and IP Address configured
