NixOS¶

Supported Releases¶

This chapter provides additional information for installing OMNeT++ on NixOS. The overall installation procedure is described in the Linux chapter.

The following NixOS releases are known to work:

• NixOS 25.11 or later

Installation Prerequisites¶

On NixOS, the dependencies come from the Nix environment that omnetpp provides, so install.sh installs no system packages; it only sets up the Python virtual environment. omnetpp assumes that certain features are enabled in your NixOS configuration. Make sure that nix.settings.experimental-features = [ "nix-command" "flakes" ]; is present in your NixOS configuration (/etc/nixos/configuration.nix).

Start the ./install.sh script in the root directory of the omnetpp installation and follow the instructions:

$ ./install.sh

After the script has finished, you can start an omnetpp session any time by typing:

# set up in the current shell
$ source setenv

# or within a new shell
$ ./setenv bash

Post-Installation Steps¶

Setting Up Debugging¶

By default, NixOS does not allow ptracing of non-child processes by non-root users. That is, if you want to be able to debug simulation processes by attaching to them with a debugger, or similarly, you want to be able to use OMNeT++ just-in-time debugging (debugger-attach-on-startup and debugger-attach-on-error configuration options), you need to explicitly enable them:

To temporarily allow ptracing non-child processes, enter the following command:

$ echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope

To permanently allow it, add

boot.kernel.sysctl."kernel.yama.ptrace_scope" = 0;

to the /etc/nixos/configuration.nix file and then rebuild your configuration.