How to create heavy file under Mac/Windows of any Extension type

•    For Windows:
1.    Go to command prompt
2.    Navigate to a folder say(cd “C:/test”)
3.    Type:  fsutil file createnew test.txt 5248 and hit enter key from keyboard.

•    For Mac:
1.    Go to terminal
2.    Navigate to location, where you want to create file
3.    Type: mkfile –v 10m test.txt
(Note: 10m demotes 10MB files, so give file size in MBs)
Note: You can change extension type of file to create any type of file like
fsutil file createnew test.jpg 5248