Alterar tela de login do usuário do ícone e plano de fundo, CentOS 7

Question

Eu tenho o CentOS 7 e quero o usuário do ícone na tela de login ...

Eu estava tentando no System Settings - > Account Details , clique na imagem

Mas esse método não funciona ...

A segunda parte, está mudando a imagem de fundo ...

Obrigado!

Editar

Editar

# gsettings list-keys org.gnome.login-screen
fallback-logo
disable-user-list
allowed-failures
enable-smartcard-authentication
banner-message-enable
enable-password-authentication
disable-restart-buttons
logo
enable-fingerprint-authentication
banner-message-text
# gsettings list-recursively org.gnome.login-screen
org.gnome.login-screen fallback-logo ''
org.gnome.login-screen disable-user-list false
org.gnome.login-screen allowed-failures 3
org.gnome.login-screen enable-smartcard-authentication false
org.gnome.login-screen banner-message-enable false
org.gnome.login-screen enable-password-authentication true
org.gnome.login-screen disable-restart-buttons false
org.gnome.login-screen logo '/usr/share/pixmaps/fedora-gdm-logo.png'
org.gnome.login-screen enable-fingerprint-authentication true
org.gnome.login-screen banner-message-text ''
# gsettings get org.gnome.login-screen logo
'/usr/share/pixmaps/fedora-gdm-logo.png'

Agora defina meu novo logotipo de imagem!

# gsettings set org.gnome.login-screen logo '/usr/share/pixmaps/faces/penguin.jpg'

(process:5208): dconf-WARNING **: failed to commit changes to dconf: The connection is closed
#