Running act through Nix

 $ sudo install -d -m755 -o $(id -u) -g $(id -g) /nix
 $ curl -L | sh

Uses the install command, which per it's man page: This install program copies files (often just compiled) into destination locations you choose.

I ran into this problem the next time I restarted by machine, where upon logging into my desktop environment, I received a message about an error while parsing the .profile file. Upon inspection, the Nix installation script added a pair of lines to .profile that looked like

 if [ -e /home/chrism/.nix-profile/etc/profile.d/ ]; 
    then . /home/chrism/.nix-profile/etc/profile.d/; 
 fi # added by Nix installer

However, the first of those, which simply had -e was not recognized, and threw an error. By entering into the system in headless mode, I was able to remove that line, which allowed the rest of the system to boot fine, and Nix to become available. At that point, following the basics of the Nix Book with commands like $ nix-shell -p hello seemed to work fine.

At this point, we were trying to run act. Per the README page, first we needed to install Docker Engine (since I'm on Pop!_OS, I followed the Ubuntu instructions). At this point however, I ran into a Docker socket issue when trying to run the act default command. After a little searching, I found the solution to this problem in a StackOverflow post, which allows the socket connection.

 # run this line to allow the Docker connection
 $ sudo setfacl --modify <your_username>:rw /var/run/docker.sock

On an Odroid-N2+ running Armbian, $ sudo softy, select Docker and hit "Install". Softy is a built-in package manager for installing common packages for Armbian. setfacl doesn't work on Armbian, though, so using

 $ sudo usermod -aG docker $USER
 $ sudo reboot