On the Sys doc I can see there is a function to create a directory, I guess the string argument is the directory's name, however I don't know what the int argument is for.
val mkdir : string -> int -> unit
Create a directory with the given permissions. [Since 4.12.0]
It may be related to the second argument of the function of the same name in Unix:
val mkdir : string -> file_perm -> unit
Create a directory with the given permissions (seeUnix.umask).
But it doesn't help me that much either.
What should I use for this argument if I want to create a directory to create files in?