Write a Bash script named indexer. This script should take a path to a directory as a command line argument. If one is

not provided or the argument is not a valid directory, you should print an error message and exit. Otherwise, your program

should print nothing.

In each directory in the inputted directory recursively, including the inputted directory itself, you should create a file named

index.json. If one is already present, you should overwrite it$.$ No other files should be created, deleted, or modified.

index.json should be a JSON file that contains lists of the regular files and directories in that directory, and a relative

path back to the inputted directory. Your code should work correctly even if any filenames have spaces.

Directories may contain a file named $\_$special and$/$or a file named $\_$blacklist. Both of these files, if present, will have a

single filename on each line. If a file is in a directory$$s $\_$blacklist, it shouldn$$t be included in that directory$$s index.json.

If a file is in a directory$$s $\_$special, the file should go into a different section of that directory$$s index.json. Neither the

$\_$blacklist nor $\_$special files themselves should be included in any index.json file lists