Listed below are few handy tools to monitor Linux system performance:

System Monitoring: This is a graphical tool available in GUI mode, similar to Taskbar iin Windows,where we are have a real time monitoring of CPU usage, memory usage, history, etc.

top : A linux process monitoring command, that refreshes in 5 seconds, that displays CPI, memory usage, swap memory, Process IDs, users, etc

vmstat or sysstat: Displays statistics of the virtual memory, the kernel threads, disks, CPU activity, interrupts, etc

lsof : List of Open Files. This command shows all files that are in open state. This is a command used to check is a specific file is opened, or a backup does not happen since a file is in open state, etc. You may use lsof command with grep to narrow the output.

netstat : A command to get Network statistics to see the listening or established network ports, who is accessing the connection, etc.

iotop : Monitor and display real-time disk IO.

iostat : Is a tool to collect the storage device IO statistics, including reads, writes, etc. This is installed by yum package sysstat

tcpdump : A tool to sniff the network interface. Network packet analyser. The command “tcpdump -i eth0” shows

uptime : Find the uptime of a system

ps : Find the processes running on a host. The command “ps -eaf” is a very useful switch.

free : Command to find the memory utilization in a host. The command “free -m” is a very useful switch to see output in MB.

mpstat : Command to see the activities for available processors in a host. The command “mpstat -P ALL” is a very useful switch.

tracepath : Trace the path taken by host to reach a destination

ping : Check the availability of a remote host