Code to move a file to /system ?

Im a galaxy s6 user here, I found out that the switch recent app button (the one on the left of the home button) quite annoying while playing game like vainglory because I misclicked it quite often. After doing some research I found out that it is possible to comment out the key 254 of generic.kl under system/usr/keylayout, then i come out with an idea of creating a new generic.kl which commented out the key 254, then with a click of button on my app it will move the file with the commented key to system/usr/keylayout to replace the old way, vice versa, I will make a restore button there to restore it will the original generic.kl when I wan the recent app switch to start working again. So my question here is what would be the code to move a file to system and replace it? I do have some basic android programming knowledge and my phone is rooted.

Thanks in advance.