If you want to restart/reboot your Android device connected over adb shell, you can do the the same using “adb reboot” command from Linux/Windows host machine.
The Simple “adb reboot” command just restarts your Android mobile/device. Android also supports other options as,
$ adb reboot
Only Restarts your Android device from host.
$ adb reboot recovery
Restarts the android device into recovery mode.
$ adb reboot bootloader
Restarts the android device into bootloader mode.
$ adb reboot sideload
Restarts into recovery and automatically starts sideload mode.
$ adb reboot sideload-auto-reboot
sideload-auto-reboot is the same as “adb reboot sideload” but reboots after sideloading.