Sstrhsrtj

I would like to know if there is a way to create a trash by intercepting calls to unlink. Theoretically files would be timestamped and deleted after set time period.

Yes, there is. The general mechanism for this type of thing (overriding a standard function) is called LD_PRELOAD. The general idea is pretty simple, when loading libraries into memory for a program, whichever one is the first to define a given symbol name defines what that symbol does. So, LD_PRELOAD lets you tell the dynamic linker to load specific libraries before all others (including libc), meaning that they can override specific functions from libraries which would be loaded later.

Examples of widely used projects that make use of LD_PRELOAD include:

• 
  jemalloc Can be pre-loaded to let you use the jemalloc memory allocator with programs that don't explicitly use it themselves.


• 
  datefudge Lets you fake the system time and date.


• 
  libeatmydata Overrides sync() and related calls to do nothing, improving performance of some applications at the cost of data safety.


• 
  dante Includes a command that uses LD_PRELOAD to enable SOCKS protocol usage for applications which don't natively support it.

There's also a library that does exactly what you're asking about called libtrash. The official web-page can be found here. I'm not sure if it works or not as I've never used it myself, but there was a recent release of a new version so it looks like the author is at least still maintaining it.