[veronika@zaglotova ~]$ sudo systemctl enable earlyoom
Created symlink /etc/systemd/system/multi-user.target.wants/earlyoom.service → /usr/lib/systemd/system/earlyoom.service.
[veronika@zaglotova ~]$
[veronika@zaglotova ~]$ sudo systemctl --type=service --state=active
  UNIT                                                LOAD   ACTIVE SUB     DESCRIPTION                                                               >
  bumblebeed.service                                  loaded active running Bumblebee C Daemon                                                        >
  cpupower-gui-helper.service                         loaded active running cpupower-gui system helper                                                >
  dbus.service                                        loaded active running D-Bus System Message Bus                                                  >
  kmod-static-nodes.service                           loaded active exited  Create list of static device nodes for the current kernel                 >
  lightdm.service                                     loaded active running Light Display Manager                                                     >
  lvm2-lvmetad.service                                loaded active running LVM2 metadata daemon                                                      >
  lvm2-monitor.service                                loaded active exited  Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress poll>
  NetworkManager.service                              loaded active running Network Manager                                                           >
  polkit.service                                      loaded active running Authorization Manager                                                     >
  rtkit-daemon.service                                loaded active running RealtimeKit Scheduling Policy Service                                     >
  systemd-backlight@backlight:intel_backlight.service loaded active exited  Load/Save Screen Backlight Brightness of backlight:intel_backlight        >
  systemd-binfmt.service                              loaded active exited  Set Up Additional Binary Formats                                          >
  systemd-fsck@dev-sda1.service                       loaded active exited  File System Check on /dev/sda1                                            >
  systemd-journal-flush.service                       loaded active exited  Flush Journal to Persistent Storage                                       >
  systemd-journald.service                            loaded active running Journal Service                                                           >
  systemd-logind.service                              loaded active running User Login Management                                                     >
  systemd-modules-load.service                        loaded active exited  Load Kernel Modules                                                       >
  systemd-random-seed.service                         loaded active exited  Load/Save Random Seed                                                     >
  systemd-remount-fs.service                          loaded active exited  Remount Root and Kernel File Systems                                      >
  systemd-swap.service                                loaded active exited  Manage swap spaces on zram, files and partitions.                         >
  systemd-sysctl.service                              loaded active exited  Apply Kernel Variables                                                    >
  systemd-tmpfiles-setup-dev.service                  loaded active exited  Create Static Device Nodes in /dev                                        >
  systemd-tmpfiles-setup.service                      loaded active exited  Create Volatile Files and Directories                                     >
  systemd-udev-trigger.service                        loaded active exited  Coldplug All udev Devices                                                 >
  systemd-udevd.service                               loaded active running Rule-based Manager for Device Events and Files                            >
  systemd-update-utmp.service                         loaded active exited  Update UTMP about System Boot/Shutdown                                    >
  systemd-user-sessions.service                       loaded active exited  Permit User Sessions                                                      >
  thermald.service                                    loaded active running Thermal Daemon Service                                                    >
  udisks2.service                                     loaded active running Disk Manager                                                              >
  upower.service                                      loaded active running Daemon for power management                                               >
  user-runtime-dir@1000.service                       loaded active exited  User Runtime Directory /run/user/1000                                     >
  user@1000.service                                   loaded active running User Manager for UID 1000                                                 >
  wpa_supplicant.service                              loaded active running WPA supplicant                                                            >

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

33 loaded units listed.
[veronika@zaglotova ~]$ sudo systemctl --type=service --state=active | grep oom
[veronika@zaglotova ~]$ sudo systemctl --type=service | grep oom
[veronika@zaglotova ~]$ sudo systemctl --type=service | grep -i oom
[veronika@zaglotova ~]$ sudo systemctl status earlyoom.service
● earlyoom.service - Early OOM Daemon
     Loaded: loaded (/usr/lib/systemd/system/earlyoom.service; enabled; vendor preset: disabled)
     Active: inactive (dead)
       Docs: man:earlyoom(1)
             https://github.com/rfjakob/earlyoom