“faketime” is a command-line tool in Linux-based systems that allows a user to run a command with a fake system time. This means that the command will see a different system time than the actual one, allowing the user to test how the command behaves under different time conditions.
faketime works by intercepting calls to the system time functions and replacing the actual time with a fake time. The fake time can be specified in various ways, such as a specific date and time, or a relative offset from the current time. For example, you can use faketime to test how a program behaves when the system time is set to a specific date in the past or future, or to test how a program handles leap years or daylight saving time changes.
It is important to note that faketime does not change the system time, it only changes the time seen by the command it runs. This means that other programs and processes running on the system will still see the actual system time. Also, faketime does not affect the hardware clock or the system time in any way. It only affect the time returned by time() and similar functions.
faketime Command Examples
1. Fake the time to this evening, before printing the result of `date`:
faketime 'today 23:30' date
2. Open a new `bash` shell, which uses yesterday as the current date:
faketime 'yesterday' bash
3. Simulate how a program would act next Friday night:
faketime 'next Friday 1 am' path/to/program