Configure GDM graphical login banner text

if ! rpm -q gdm >/dev/null 2>&1; then exit 0; fi
# Check banner-message-enable is true
enable=$(grep -rhs '^\s*banner-message-enable\s*=' \
  /etc/dconf/db/gdm.d/ /etc/dconf/db/local.d/ 2>/dev/null |
  tail -1 | grep -io 'true' || true)
if [ -z "$enable" ]; then
  enable=$(DCONF_PROFILE=/etc/dconf/profile/gdm dconf read \
    /org/gnome/login-screen/banner-message-enable 2>/dev/null || true)
fi
if [ "$enable" != "true" ]; then
  echo "FAIL: banner-message-enable is not true"
  exit 1
fi
# Check banner-message-text is set and non-empty
text=$(grep -rhs '^\s*banner-message-text\s*=' \
  /etc/dconf/db/gdm.d/ /etc/dconf/db/local.d/ 2>/dev/null |
  tail -1 | sed "s/^[^=]*=\s*//;s/^['\"]//;s/['\"]$//" || true)
if [ -z "$text" ]; then
  text=$(DCONF_PROFILE=/etc/dconf/profile/gdm dconf read \
    /org/gnome/login-screen/banner-message-text 2>/dev/null |
    sed "s/^'//;s/'$//" || true)
fi
textlen=$(echo "$text" | tr -d '[:space:]' | wc -c)
if [ "$textlen" -lt 20 ]; then
  echo "FAIL: banner-message-text is empty or too short ($textlen chars)"
  exit 1
fi
echo "OK: GDM banner enabled with $textlen chars of text"

expected_exit:

0

note:

Banner text is organization-specific and must be customized. Create /etc/dconf/db/gdm.d/00-security-settings with: [org/gnome/login-screen] banner-message-text='<your organization consent banner>' Then run: dconf update