[Linux] How to set limit on memory usage in a shell?

Occasionally, my computer crashed when I ran a program which ate up all the memory. To prevent this from happening again, I want to set a limit on the memory usage in a shell, so any command run in that shell will be limited to set memory usage.

My system

OS: Ubuntu 22.04

Solution not working

I searched Google and many suggested to use

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ulimit -m <value>

to set memory usage, but it did not work – no restriction on memory at all.

Solution

I eventually went with the following solution:

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ulimit -v <value>
# example for 40KB
ulimit -v 40

This command sets the maximum virtual memory size for the shell, and it worked.

The command ulimit -m is supposed to limit the Resident Memory Size (RSS), and the command ulimit -v is supposed to limit the Virtual Memory Size (VMS), which includes RSS and swapped/shared memories. Therefore, the command ulimit -v is more stringent for the total memory usage.

Another solution

One may also try to use the following command, but I have not tried it yet:

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systemd-run --scope --user -p MemoryMax=250M -- /path/to/program/to/use

Happy Programming 😄.

Last modified on 2025-04-12