nmon

What nmon is

nmon is a free Linux tool for systems administration, performance tuning, and benchmarking. It collects performance information and displays it live in a terminal through a curses interface. Keyboard controls let users choose which kinds of data appear, including CPU, memory, network, disks, filesystems, NFS, and top processes. The Linux version also displays resources and processors. nmon can save performance data to a comma-separated file for later analysis or longer-term capture.

For working with captured data, nmonchart turns output into graphs for a webpage, while nmon Analyser loads output into an Excel spreadsheet and creates graphs. The project also describes njmon injectors for adding JSON data to InfluxDB and Splunk, and real-time graphing with InfluxDB and Grafana. Binaries are listed for POWER and x86/AMD64 Linux distributions, with separate builds for mainframe Linux; supported platforms also include ARM. Where a suitable binary is unavailable, the site directs users to compile from source with GCC and the ncurses development library. The Linux project is licensed under GPLv3. nmon for AIX is integrated into the AIX topas command and is not open source.

Who it suits

nmon suits system administrators, developers, and advanced users who need to view or capture Linux performance data. It is also relevant to teams that want to analyze saved output or connect JSON data to InfluxDB or Splunk.

Limits

nmon is free. For Linux platforms or distributions without a matching binary, the site directs users to compile from source with GCC and the ncurses development library.

Getting started

1. Visit the nmon website.
2. Choose a Linux build for a supported platform, or compile from source with GCC and the ncurses development library if there is no matching binary.
3. Run nmon in a terminal and use its keyboard controls to select displayed data.
4. Save performance data to a comma-separated file for later analysis if needed.

Verdict

Choose nmon if you need free Linux performance monitoring with both live terminal data and CSV capture. Look elsewhere if you need a matching prebuilt binary for your Linux distribution and cannot compile from source, or if an open-source AIX version is required.