When CONFIG_APP_FOTA_SHELL is enabled:
att_fota poll # Poll nRF Cloud for pending firmware updates
The poll command publishes a FOTA_POLL_REQUEST on fota_chan, instructing the FOTA module to check nRF Cloud for available firmware updates. If an update is available, the FOTA module starts the download automatically. See the Firmware updates (FOTA) guide for more details.