In my programming work, I often need to know the memory used by web applications. A rough estimate is usually enough before getting down to details and browser profiling tools.

To interrogate memory use on Linux or macOS, people typically use top or htop. I'd love to see a single number: How much RAM did a process take. But statistics shown by these utilities can be hard to understand. With web browsers, it's even more complicated because they often run many separate processes. They all show up in top output as a long list, each with its own individual metrics.

Image by:

^{(Tomasz Waraksa, CC BY-SA 4.0)}

Enter smem command

Luckily there is smem, another command-line utility for viewing memory use statistics. Install it with your package manager of choice, for example:

sudo apt install smem

To get total memory use by Firefox, do:

smem -c pss -P firefox -k -t | tail -n 1

What happens here?

• -c switch specifies columns to show. I'm only interested in the pss column, which shows memory allocated by a process.
• -P switch filters processes to include only those with firefox in the name
• -k switch tells to show memory use in mega/gigabytes instead of plain bytes
• -t switch displays the totals
• tail -n 1 filter outputs only the last line, just where the totals are

The output is as simple as it gets:

$ smem -t -k -c pss -P firefox | tail -n 1
4.9G

Straight to the point! And, after another busy day of work, with over fifty opened tabs, Firefox still uses only 5 GB. Take that, Google Chrome ;-)

Even easier with a script

For convenience, create a little script named memory-use, which takes the process name as a parameter. I keep all my scripts in ~/bin, so:

echo 'smem -c pss -P "$1" -k -t | tail -n 1' > ~/bin/memory-use && chmod +x ~/bin/memory-use

Now I can measure memory use of any application as easy as:

memory-use firefox
memory-use chrome
memory-use slack

And there is even more!

The utility can do much more than show the total memory use. It can even generate graphic output.

For example:

smem --pie name -c pss

Shows something like this:

Image by:

^{(Tomasz Waraksa, CC BY-SA 4.0)}

For more details, I recommend looking into smem man pages.

You can find another great tutorial at https://linoxide.com/memory-usage-reporting-smem/.

Enjoy!

This article originally appeared on the author's blog and is republished with permission.