Yes if you take it to the shelter it will be pts.

Start putting food out for it at set times. Keep in mind this will encourage other wildlife, namely skunks, possums, raccoons! So think before you do this! This is the way to work up to petting it. Then having it walk inside, then keeping it, having it fixed etc. Oh, and once you start feeding it, some communities consider it YOURS so if it bites someone you are responsible for it not having up to date rabies shot.

OR you can borrow a trap and trap it. There should be a feral cat rescue in your area, which offers traps and low cost spay / neuter programs. A cat who is afraid of humans had to be brought to the vet in the trap and not all vets will work on such. This is why you would work with a program. They can help decide if it needs to be fixed and returned to the wild, or tamed up.

To find a program, you can use Google and put TNR cat xxx where xxx is your city / town. Or you can post asking on your local craigslist -- someone out there will answer you!

Good luck!