Essential System Utilities: bottom – graphical process/system monitor for the terminal

Last Updated on May 2, 2023

In Operation

Start bottom with the btm command.

We’ve shoehorned our terminal to match the width available on our template so things look a mite squashed and some of the information is not displayed.

Let’s go through the widgets. At the top is the CPU widget showing the CPU usage across all the cores. The time range can be adjusted with a range of 30s to 600s. The box adjacent tells you we’re testing bottom on a machine with 6 cores. We can monitor individual cores by moving up and down the CPU list, or the average CPU usage.

Below the CPU widget is the Memory widget showing a visual representation of RAM. It also shows swap usage but this test system has no swap partition or file configured (32GB of RAM with no swap is  sufficient for our testing purposes). Again the time range can be adjusted with a range of 30s to 600s. Adjacent are widgets reporting system temperatures and disks. The latter has more information than shown in the image above. There are columns for mount point, % used space, free space, total, amount of space, read per second, and write per second.

You’ll see that our test system is plagued by snaps being mounted and listed as block devices. The test system has an alias for df $ alias df='df -h -x squashfs -x tmpfs' which removes all that noise when using df.

The bottom widgets show network activity and a process list. The process list displays for each progress its CPU usage, memory usage, reads per second, writes per second, total read, total write, the user of the process and its state.

There is also a battery widget available which provides information about the batteries on the system: charge percent, consumption, time to empty/charge and the battery health percent. The widget supports devices with more than 1 battery.

There are lots of nice touches present. For example, pressing the e key (or starting bottom with the -e flag) expands the current widget so that it occupies the entire space. There is a basic mode ($ btm -b) which dispenses with the graphs which is useful if you prefer monitoring in a small window.

You’ll want to learn the keyboard shortcuts. Press ? to bring them up. There are general keybindings as well as specific keybindings for each widget. Below we’ve reproduced the bindings for the process widget:

dd, F9           Kill the selected process
c                Sort by CPU usage, press again to reverse
m                Sort by memory usage, press again to reverse
p                Sort by PID name, press again to reverse
n                Sort by process name, press again to reverse
Tab              Group/ungroup processes with the same name
Ctrl-F, /        Open process search widget
P                Toggle between showing the full command or just the process name
s, F6            Open process sort widget
I                Invert current sort
%                Toggle between values and percentages for memory usage
t, F5            Toggle tree mode
+, -, click      Collapse/expand a branch while in tree mode
click on header  Sorts the entries by that column, click again to invert the sort

Next page: Page 3 – Summary

Pages in this article:
Page 1 – Introduction / Installation
Page 2 – In Operation
Page 3 – Summary

Complete list of articles in this series: