Nmon (also known as Nigel’s Monitor) is a computer performance system monitor tool for the AIX and Linux operating systems developed by IBM employee Nigel Griffiths. The tool displays onscreen or saves to a data file the operating system statistics to aid in the understanding of computer resource use, tuning options and bottlenecks. This system benchmark tool gives you a huge amount of important performance information in one go with a single command. You can easily monitor your system’s CPU, memory, network, disks, file systems, NFS, top processes, resources and power micro-partition information using Nmon.
### Installing Nmon ###
By default nmon is available in the Ubuntu repository. You can easily install nmon by running the following command:
sudo apt-get install nmon
How to Use Nmon to Monitor Linux Performance
Once the installation has been finished, you can launch it by typing the `nmon` command in the terminal.
You can see from the above screenshot that the nmon command-line utility runs completely in interactive mode, and you can easily toggle statistics using shortcut keys.
You can use the following nmon keyboard shortcuts to display different system stats:
-`q` : to stop and exit Nmon
-`h` : to see help screen
-`c` : see CPU stats
-`m` : see memory stats
-`d` : see disk stats
-`k` : see kernel stats
-`n` : see network stats
-`N` : see NFS stats
-`j` : see file system stats
-`t` : see top process
-`V` : see virtual memory stats
-`v` : verbose mode
### Check CPU by Processor ###
If you would like to collect some statistics on CPU performance, you should hit the c key on the keyboard.
After hitting the c key you wI’ll see the following output.
A very useful key for every system admin is the `r` key which is used to give information on different resources such as machine architecture, operating system version, Linux version and CPU.
You will see the following output by hitting the `r` key.
There are many other tools that can do the same job of the Nmon, but Nmon is so usee friendly for a Linux beginner. Please feel free to comment if you have any questions.
