A door bar bracket does not have to be difficult to find. Door bar brackets are available in various styles and materials. You can find sliding door bar brackets, shower door bar brackets as well as metal door bar brackets among other products. Functional door brackets need to fit the door model you're installing, especially since they are constructed differently and are available in various sizes.
Sliding doors such as closet doors, patio doors or French doors for example utilizes different types of brackets from regular hinged doors which usually is used for entrances or for separation between different rooms. Before you purchase the product, you want to make sure you have the right size in order and the type that you need. Home Depot and Lowes are two stores which would certainly be worth a visit, however if you can't find exactly what you need there, then the web is a wonderful place since it provides so many options.
C.R. LAURENCE M6078 CRL Chrome Offset Sliding Shower Door Towel Bar Bracket
"C.R. LAURENCE M6078 CRL Chrome Offset Sliding Shower Door Towel Bar Bracket. The plated diecast CRL Offset Towel Bar Bracket has a 8-32 internal threaded stud and accepts a 3/8 by 3/4 inch (9.5 by 19.1 millimeter) towel bar. It can be used on both shower and tub enclosure doors.."
Westward 4PE60 Door Hanger Bracket Kit
"Westward Door Hanger Bracket Kit 4PE60 Hanger Kit Barn Door Hardware Door Hanger Bracket Kit Size 2 1/8 Inches Finish US2C-Bright Zinc For Doors W "
These brackets can be found at amazon.com