SYSTEM MONITOR Atop
Version: 2.10.0 Web: www.atoptool.nl
Long-time Linux users and CLI warriors will be familiar with the Top system monitor and its newer, colourful and more interactive cousin, Htop. For a much deeper look into the system, however, you need Atop. It displays tons of information related to the amount of load on the system’s resources at the process level.
The app is available in the official repos of popular distros. Ubuntu users can use sudo apt install atop to install the app, while sudo dnf install atop installs the app in Fedora.
Once installed, type atop in the terminal to fire up the tool. Since it can display privileged information, it’s best run with superuser privileges, such as sudo atop .
Atop’s layout is divided into two panels. The upper panel provides the cumulative use of the system’s resources, whereas the bottom one displays disintegrated information for each process.
By default, it shows system activity for CPU, memory, swap, disks and network. In addition, for each process and thread, you can analyse CPU utilisation, memory consumption, disk I/O, priority, username, state and a lot more.
The good thing about Atop is that it stays active in the background, recording all activity, which makes it a good option for long-term analysis. By default, it writes snapshots to a compressed log file in /var/log/atop. These files are named atop_yyyymmdd. For example, atop_20240102 is the log for 2nd January 2024.
This log file can be read with atop -r /var/log/atop/ atop_20240102 . When loaded, the snapshot displays a timestamp. Press t (lower case) to move forward to the next snapshot, and T (upper case) to go back to the previous snapshot.
As with most CLI utilities, it’s best to scroll through Atop’s man page to fully appreciate its true capabilities.