How to move files with adb shell?

How can I move files with adb shell ?
For example I would like to move SystemUI.apk from /system to /system/app

I didn't find any command to move files inside system partition with adb shell.
Do anyone know how to do this?

Does `mv` not work?

mv /system/SystemUI.apk /system/app/

Or perhaps you need to be root:

su
mv /system/SystemUI.apk /system/app/

you can try:
adb shell mv /system/file_path /sdcard