adb - Failed on cp file to /system - Cross-device link

I'm trying to mv .apk file from my /sdcard to /system and getting following error:

failed on 'XXX.apk' - Cross-device link

I did remount my /system as rw

root@ghost:/ # mount -o rw,remount /dev/block/platform/msm_sdcc.1/by-name/system /system
root@ghost:/ # mount | grep system                                             
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 rw,seclabel,relatime,data=ordered 0 0
root@ghost:/ # 

I also tried following, but without luck(

mbp:~ alexus$ adb root
adbd cannot run as root in production builds
mbp:~ alexus$ adb remount
remount failed: Permission denied
mbp:~ alexus$ 

Why can't I still move apk file to /system? What am I missing?

Answer

and the answer is pretty simple, use cp instead of mv)