Add global YOLOv5_DATASETS_DIR (#9586)

utils/general.py

@@ -43,8 +43,8 @@ ROOT = FILE.parents[1]  # YOLOv5 root directory
 RANK = int(os.getenv('RANK', -1))
 
 # Settings
-DATASETS_DIR = ROOT.parent / 'datasets'  # YOLOv5 datasets directory
 NUM_THREADS = min(8, max(1, os.cpu_count() - 1))  # number of YOLOv5 multiprocessing threads
+DATASETS_DIR = Path(os.getenv('YOLOv5_DATASETS_DIR', ROOT.parent / 'datasets'))  # global datasets directory
 AUTOINSTALL = str(os.getenv('YOLOv5_AUTOINSTALL', True)).lower() == 'true'  # global auto-install mode
 VERBOSE = str(os.getenv('YOLOv5_VERBOSE', True)).lower() == 'true'  # global verbose mode
 FONT = 'Arial.ttf'  # https://ultralytics.com/assets/Arial.ttf