The Fake Time Preload Library (FTPL, a.k.a. libfaketime) intercepts
various system calls which programs use to retrieve the current date and time.
It can then report faked dates and times (as specified by you, the user) to
these programs. This means you can modify the system time a program sees
without having to change the time system-wide. FTPL allows you to specify both
absolute dates (e.g., 2004-01-01) and relative dates (e.g., 10 days ago).