Which command do you issue to upgrade the current software on Junos devices?

Upgrading the Junos OS
Use the request system software add path/image name CLI command to upgrade the Junos OS. You can specify a
local path and file name or a remote FTP or SCP URI that contains the required Junos image to download and install. To activate
the new software, you must reboot the system. You can perform the system reboot as a separate step or you can initiate it by
adding the reboot option at the end of the request system software add command.
Once the Junos OS is installed, you are notified that the system is rebooting to complete the installation. Use a console
connection to view details of the upgrade process. Watch for any error messages indicating a problem with the upgrade.
Devices running the Junos OS execute binaries supplied only by Juniper Networks. Each Junos image includes a digitally signed
manifest of executables that are registered with the system only if the signature can be validated. The Junos OS does not
execute any binary without a registered fingerprint. This feature is designed to protect the system against unauthorized software
and activity that might compromise the integrity of your device running the Junos OS.