On 2020-05-02, at 10:12, to...@tuxteam.de wrote:
> On Sat, May 02, 2020 at 09:37:40AM +0200, Marcin Borkowski wrote: >> >> On 2020-04-30, at 07:02, Kyle Meyer <k...@kyleam.com> wrote: >> >> > And note that a utility like datefudge or libfaketime is useful for >> > testing these sorts of things out. For example: >> > >> > $ datefudge "2020-02-18" emacs [...] >> >> Shameless plug: I wrote about this use-case of datefudge sime time ago: >> http://mbork.pl/2019-08-05_datefudge_and_agenda_testing >> >> (I don't know libfaketime). > > It just plays games with LD_PRELOAD to trick the application (which is > supposed to use the usual libs when asking for time, but most do that). > > Infinitely more lightweight than a container or a VM. On Debian: > > tomas@trotzki:~$ apt show libfaketime > Package: libfaketime > [...] > Download-Size: 31.2 kB > APT-Sources: http://ftp.de.debian.org/debian buster/main amd64 Packages > Description: Report faked system time to programs (preload library) > The Fake Time Preload Library (FTPL, a.k.a. libfaketime) intercepts > various system calls which programs use to retrieve the current date > and time [...] FTPL allows you to specify both absolute dates (e.g., > 2004-01-01) and relative dates (e.g., 10 days ago). > > You might need a VM for an app which bypasses the "usual libraries", > but then, I don't know whether I would like to have such a thing on > my box. Probably not without a good reason :-) One use-case when this might be reasonable is an application which talks to a database, when you have to convince both the application and the database server that the time is different than in reality. Best, -- Marcin Borkowski http://mbork.pl
