Most people don't think about how to fix a safe to a wall until they've already bought the safe and are ready to install it. There are a few different ways that you can fix a safe to a wall, and the method you choose will depend on the type of safe you have, as well as the weight of the contents you'll be storing inside.
If you have a small home safe, the easiest way to install it is by using heavy-duty adhesive strips. Simply clean the surface of your chosen installation spot with rubbing alcohol, peel off the backing on the adhesive strips, and press the safe firmly into place. For extra security, you can also screw the safe into your wall studs using long screws.
If you have a larger gun safe or commercial-grade safe, it's best to bolt it down for maximum security. You'll need to drill holes into both your floor and walls (into studs if possible), then insert large bolts or lag screws through these holes and tighten them down with washers and nuts. It's important that you use high-quality hardware that is rated for outdoor use, as regular household bolts may not be strong enough to withstand attempts at forced entry.