how to make the contents of a file disappear after x numbers of days or at date

[Patton Echols]

user1 wrote:
>  
>   
>> Why not tell us what you are actually trying to achieve? Maybe if you
>> told us the actual problem, we could suggest other ways to solve it.
>>     
>
> Lets say I want to send a picture to a person - then I do not want the 
> person to copy it and use it for "some purpose" - the person is not an 
> expert, so after a day in his posession the contents of the image 
> disappears - same idea with a text file?
>
>   

I don't know a solution.  But have a memory that may further your thinking.

I seem to recall a version of PGP (under DOS) years ago that allowed a 
user to encrypt a file into an executable wrapper.  When executed, the 
wrapper would spawn a viewer in "protected memory" that prevented 
copying.  The trick was that the wrapper could be set with an expiration 
date.  Execution of the wrapper would fail after that date.

I have no idea if anything still exists or ever existed for linux.  The 
problem with such a system is that I can think of several possible work 
arounds. 

Good luck