How to Use the Start File Name Parameter in the Backblaze B2 Native API

This article provides details about the startFileName parameter in the b2_list file_names API.

The following example shows a bucket's possible folder structure.

cats/
  photo1.jpg
  photo2.jpg
kittens/
  video1.jpg
  video2.jpg
cats-readme.txt

If you want the files and folder structure at the level "cats," the prefix for startFileName should be cats/.

If you want the file and folder structure at the level "kittens," the prefix for startFileName prefix should be kittens/.

The trailing slash is important. Without it, the first file in the list that should be returned would be cats-readme.txt instead of cat/photo1.jpg.

For each bucket, Backblaze B2 keeps an internal, alphabetically sorted list of the files in that bucket. When you specify a startFileName, it gives you that file and the next 1000 files (of the number given to maxFileCount).

The folder structure example above would be returned by b2_list_file_names in alphabetical order:

cats-readme.txt
cats/photo1.jpg
cats/photo2.jpg
kittens/video1.jpg
kittens/video2.jpg