When is it okay to check if a file exists?

Question

File systems are volatile. This means that you can\'t trust the result of one operation to still be valid for the next one, even if it\'s the next line of code. You can\'t

Answer 1

Like you pointed out its always important what the program should do if the file is missing. In all my applications the user can always delete the config file and the application will create a new one with default values. No Problem. I also ship my applications without config files.

But users tend to delete files and even files they should not delete like serial keys and template files. I always check for these files because without them the application is unable to run at all. I can not create a new serial key from default.

Whats should happen when the file is missing? You can do a file find or exception handler but the real question is : What will happen when the file is missing? Or how important is the file for the application. I check all the time before I try to access any support files for the app. Additional I do error handling if the file is corrupt and can not be loaded.