nixos/tests/pantheon: Always use `pgrep -xf`

          machine.succeed("getfacl -p /dev/snd/timer | grep -q ${user.name}")

      with subtest("Check if Pantheon components actually start"):

          pgrep_list = [

              "${pkgs.pantheon.gala}/bin/gala",

              "io.elementary.wingpanel",

              "io.elementary.dock",

              "${pkgs.pantheon.gnome-settings-daemon}/libexec/gsd-media-keys",

              # We specifically check gsd-xsettings here since it is manually pulled up by gala.

              # https://github.com/elementary/gala/pull/2140

          for i in ["gala", "io.elementary.wingpanel", "io.elementary.dock", "gsd-media-keys", "gsd-xsettings", "io.elementary.desktop.agent-polkit"]:

              machine.wait_until_succeeds(f"pgrep -f {i}")

          machine.wait_until_succeeds("pgrep -xf ${pkgs.pantheon.elementary-files}/libexec/io.elementary.files.xdg-desktop-portal")

              "${pkgs.pantheon.gnome-settings-daemon}/libexec/gsd-xsettings",

              "${pkgs.pantheon.pantheon-agent-polkit}/libexec/policykit-1-pantheon/io.elementary.desktop.agent-polkit",

              "${pkgs.pantheon.elementary-files}/libexec/io.elementary.files.xdg-desktop-portal"

          ]

          for i in pgrep_list:

              machine.wait_until_succeeds(f"pgrep -xf {i}")

      with subtest("Check if various environment variables are set"):

          cmd = "xargs --null --max-args=1 echo < /proc/$(pgrep -xf ${pkgs.pantheon.gala}/bin/gala)/environ"

          machine.succeed(f"{cmd} | grep 'SSH_AUTH_SOCK' | grep 'gcr'")

      with subtest("Wait for elementary videos autostart"):

          machine.wait_until_succeeds("pgrep -f io.elementary.videos")

          machine.wait_until_succeeds("pgrep -xf /run/current-system/sw/bin/io.elementary.videos")

          machine.wait_for_text("No Videos Open")

          machine.screenshot("videos")