When you need a lightweight terminal monitor for CPU, memory, disk, and network activity, you can install nmon on Ubuntu in a minute from the default repositories instead of hunting for a separate download. It works well on desktop systems and remote SSH sessions, and it can write .nmon capture files for later analysis in a spreadsheet or other reporting tool.
Nmon is available for Ubuntu 26.04 (Resolute Raccoon), 24.04 (Noble Numbat), and 22.04 (Jammy Jellyfish), although the packaged release differs by LTS. The commands stay the same across all three versions, so you can move from a quick interactive check to a short recording run without changing the workflow.
Update Ubuntu Before Installing Nmon
Refresh the package index before installing nmon so APT sees the latest package metadata from your configured Ubuntu repositories.
sudo apt updateIf your account does not have
sudoaccess yet, set that up first with add a new user to sudoers on Ubuntu.
Install Nmon on Ubuntu with APT
Install nmon on Ubuntu with sudo apt install nmon from the default repositories. If APT cannot locate the package on a custom or trimmed image, enable Universe and Multiverse in Ubuntu, then refresh APT again.
sudo apt install nmonVerify the installed package state with apt-cache policy. The table above uses the short upstream release names 16s, 16p, and 16n, while APT shows the full Ubuntu package revisions such as 16s+debian-1, 16p+debian-1, and 16n+debian-1.
apt-cache policy nmonExpected output excerpt on Ubuntu 26.04:
nmon:
Installed: 16s+debian-1
Candidate: 16s+debian-1
Version table:
*** 16s+debian-1 500
100 /var/lib/dpkg/status
Default Nmon Versions by Ubuntu Release
The packaged nmon release differs by Ubuntu LTS, but the installation and day-to-day commands stay the same.
| Ubuntu Release | Default Nmon | Support Status | Best For |
|---|---|---|---|
| Ubuntu 26.04 | Nmon 16s | Newest supported Ubuntu LTS default | Fresh installations wanting the latest packaged nmon release |
| Ubuntu 24.04 | Nmon 16p | Current stable Ubuntu LTS default | Established 24.04 systems needing the current LTS package |
| Ubuntu 22.04 | Nmon 16n | Oldest maintained Ubuntu LTS default | Older 22.04 systems staying on the supported LTS |
Launch Nmon on Ubuntu
Start the interactive dashboard with the nmon command.
nmonNmon opens a full-screen terminal interface with live system statistics and keyboard shortcuts. Press h for the built-in help screen, press q to quit, and use it over local terminals or remote shells after you install SSH on Ubuntu on the target machine.
Use Essential Nmon Keys on Ubuntu
The quickest way to get comfortable with nmon is to toggle only the views you need for the problem in front of you.
Show Nmon CPU Statistics with c and C
Press c to show per-CPU utilization bars for user, system, and idle time. On larger systems, press C for the wide summary view that keeps many cores visible on one screen.
Show Nmon Memory Statistics with m
Press m to display memory and swap usage. This is the fastest way to see whether a slowdown comes from RAM pressure, cache growth, or active swapping.
Show Nmon Network Activity with n
Press n to track per-interface receive and transmit activity, packet counts, and error rates. If you want a network-only terminal view outside nmon, install Bmon on Ubuntu for a more focused bandwidth monitor.
Show Nmon Disk Statistics with d and D
Press d in nmon to show disk busy percentages and read/write KB/s graphs. Press D to cycle the detailed disk view, which adds transfers, average block size, and peak values for deeper I/O troubleshooting.
Show Nmon Top Processes with t and u
Press t to open the top-process panel sorted by activity. Press u when you need full command lines instead of short process names, or install htop on Ubuntu if you want a dedicated process viewer with easier sorting and signal controls.
Check Nmon Filesystem Usage with j
Press j to list mounted filesystems with total size, used space, and percentage full. That is handy when an application slowdown turns out to be a space problem rather than CPU or memory pressure.
Use Additional Nmon Keys
Press h for the full help overlay, q to quit, + or - to change the refresh interval, and 0 to reset peak counters after a test run.
Capture Nmon Data Files on Ubuntu
Use recording mode when you need a shareable performance capture instead of a live dashboard. Nmon writes a comma-separated .nmon file that you can inspect with standard text tools, import into a spreadsheet, or process with the Excel-based nmon Analyser.
Start with a short test so you can confirm the output file lands where you expect. Keep -f or -F first on the command line, then add -s for the interval and -c for the total number of snapshots.
nmon -F ubuntu-nmon-test.nmon -s 1 -c 3This command collects three one-second samples and exits. Verify that the file exists before you move on to longer captures.
ls -1 ubuntu-nmon-test.nmonExpected output:
ubuntu-nmon-test.nmon
For longer sessions, switch to the automatic filename with nmon -f or increase the sample window, for example nmon -fT -s 120 -c 720 for two-minute samples across 24 hours with top-process data included. When you want the output written somewhere else, add -m /path/to/directory to set the destination directory.
Troubleshoot Common Nmon Issues on Ubuntu
Most nmon problems on Ubuntu come down to package state, terminal size, or writing the capture file to a different directory than expected.
Fix Nmon Command Not Found on Ubuntu
If nmon is still missing right after installation, confirm that the package is installed and that your shell has refreshed its command cache.
apt-cache policy nmonExpected installed-state line on Ubuntu 26.04:
Installed: 16s+debian-1
If the package is installed but the command still fails, open a new terminal or run hash -r, then try /usr/bin/nmon directly. If the candidate line is empty, enable Universe and Multiverse in Ubuntu, then refresh APT before trying again.
Fix Nmon Recording Files Not Created on Ubuntu
If you cannot find a capture after nmon -f or nmon -F, the file is usually being written to a different directory than expected. Run the command from a writable directory, use -F when you want a predictable filename, or add -m /path/to/directory to force the output into a specific location.
Fix Nmon Display Corruption on Ubuntu
If the interface looks cramped or garbled, make the terminal window larger or reduce the font size so nmon has enough rows and columns to render its panels cleanly. Press B to disable the on-screen boxes when your terminal emulator handles line drawing poorly.
Remove Nmon from Ubuntu
Remove the package with APT if you no longer need nmon on the system.
sudo apt remove --purge nmonClean up any orphaned dependencies after the package is gone.
sudo apt autoremoveVerify that APT now reports the package as removed.
apt-cache policy nmonExpected output excerpt on Ubuntu 26.04:
nmon:
Installed: (none)
Candidate: 16s+debian-1
Version table:
16s+debian-1 500
Removing the
nmonpackage does not delete the.nmoncapture files you already saved in other directories. Delete those files manually only if you no longer need the recorded data.
Nmon on Ubuntu FAQ
No. Nmon writes plain-text .nmon files, so you can inspect them with standard text tools or import them into other reporting workflows. Nmon Analyser is useful only if you specifically want its Excel-based charts and reports.
Yes. Nmon runs in a terminal, so it works in local shells and SSH sessions. Recording mode is especially useful on servers because nmon -f or nmon -F filename.nmon saves data for later review without needing a graphical desktop.
Press d to show disk busy percentages and read/write KB/s graphs. Press D to cycle the detailed disk view, which adds transfers, average block size, and peak values.
No. Removing the nmon package does not delete the .nmon files you already saved in another directory. Delete those files manually only when you no longer need the recorded data.
Conclusion
Nmon is ready on Ubuntu for quick live checks of CPU, memory, disk, and network load, and its recording mode makes it easy to save short baselines for later comparison. Start with the live dashboard, then switch to capture files when you need evidence from a test window or a slow server.
Formatting tips for your comment
You can use basic HTML to format your comment. Useful tags currently allowed:
<code>command</code>command<strong>bold</strong><em>italic</em><blockquote>quote</blockquote>