[root@amd-nixos:~]# nix-repl '<nixpkgs/nixos>'
Welcome to Nix version 1.11.6. Type :? for help.

Loading ‘<nixpkgs/nixos>’...
Added 6 variables.

nix-repl> config.systemd.services.snmpd.serviceConfig.ExecStart
"/nix/store/v1hwdl524w8gajsb5mja08vp6p45979a-net-snmp-5.7.3/bin/snmpd -f -c /nix/store/72g89va9qpf1db04plx75dn1bwkpixyc-snmpd.conf"