setenv (iBoot command)

From The Apple Wiki

setenv is an iBoot command that, when used with the autoboot-true or autoboot-false argument, can kick your iDevice into or out of Recovery mode. To use this command manually, you need to connect to the iDevice in Recovery Mode using iRecovery.

Usually, you have to save the env to the device, so after using setenv command, send the saveenv command.