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.

libfaketime allows you to specify both absolute dates (e.g., 01/01/2004)
and relative dates (e.g., 10 days ago).

libfaketime might be used for various purposes, for example

- Running legacy software with y2k bugs
- Testing software for year-2038 compliance
- Debugging time-related issues, such as expired SSL certificates
- Running software which ceases to run outside a certain timeframe
- Using different system-wide date and time settings, e.g., on OpenVZ-
  based virtual machines running on the same host
- Deterministic build processes.

WWW: https://github.com/wolfcw/libfaketime