Nmon - a nice monitoring tool for Linux

Although not as popular as top or htop, nmon is still one of the best monitoring tools for Linux. Nmon is a tuner, benchmark and system administrating tool. Nmon displays many system performance info cpu, memory, hard drive, network .. By default, nmon updates output data once every two seconds. However, you can easily change this interval to any time period that you prefer. Perhaps the nicest feature of nmon is you can also it to capture data for a period in spreadsheet output format (.csv) to study or write performance report, which can be very useful if you are administrating a linux dedicated server.

You can either use nmon directly in the terminal to check the system performance. Just hit "nmon" in the terminal and you will have the screen like the image below:

nmon, monitoring tools for linux

As you can see in the screenshot, you just need to type a letter to choose the info you want to check and hit this letter once again to turn off the info. You can hit multiple letters to display various system info. The image below is an example of using nmon to display info about cpu, memory and network performance:

check nmon monitoring tools for linux

To get the output in spreadsheet format for analysis and graphing for reports, you can use the -f option. For example, to get the report of your system performance for 30 minutes with the data updated every 15 seconds, you can use the following command:
 nmon -f -s 15 -c 120  

To know more about nmon, please check the manual of nmon and run the help option (-h) of nmon.

Installing nmon is easy since most Linux distro got nmon in their respiratory. If you use Arch Linux, the installing command will be:
 sudo pacman -S nmon  
If you use Ubuntu or other Debian-based distro, use the following command:
 sudo apt-get install nmon  
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