datefudge(1)

1DATEFUDGE(1)                        Debian                        DATEFUDGE(1)
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NAME

6       datefudge - pretend the system time is different
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SYNOPSIS

9       datefudge  [-s|--static] [-l|--add-ld-preload lib] at_date program [ar‐
10       guments ...]
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DESCRIPTION

13       datefudge is a small utility that pretends that the system time is dif‐
14       ferent  by pre-loading a small library which modifies the time(2), get‐
15       timeofday(2) and clock_gettime(2) system calls.
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DATE FORMAT

18       The at_date argument can be given in any format accepted by the date(1)
19       program,  for  example "2007-04-01 12:21" or "yesterday", or "next Fri‐
20       day".
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OPTIONS

23       --static, -s
24              Mark the date as a `static' one.   The  above  mentioned  system
25              calls will always return the date given in the at_date argument,
26              regardless of time passing.  See EXAMPLES below.
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28       --add-ld-preload lib, -l lib
29              Prepend lib to LD_PRELOAD environment variable before  executing
30              given  program.   This option might be useful for example to in‐
31              ject sanitizer libraries (e.g. from Address  Sanitizer)  to  the
32              list  of preloaded libraries before the internal datefudge's li‐
33              brary.  See EXAMPLES below.
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35       --help, -h
36              Print short usage information and exit.
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38       --version, -v
39              Print version information and exit.
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EXAMPLES

42   Basic examples:
43       $ datefudge "2007-04-01 10:23" date -R
44       Sun, 01 Apr 2007 10:23:00 +0200
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46       $ datefudge "1 May 2007" date -R
47       Tue, 01 May 2007 00:00:00 +0200
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49       $ datefudge "2 weeks ago" date -R
50       Wed, 16 Jan 2008 13:32:12 +0100
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52   Non-static vs. static example:
53       $ datefudge "2007-04-01 10:23" sh -c "sleep 3; date -R"
54       Sun, 01 Apr 2007 10:23:03 +0200
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56       $ datefudge --static "2007-04-01 10:23" sh -c "sleep 3; date -R"
57       Sun, 01 Apr 2007 10:23:00 +0200
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59   Prepending LD_PRELOAD example:
60       $ datefudge --add-ld-preload /path/to/libclang_rt.asan-x86_64.so "2007-04-01 10:23" command
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62       If the command was compiled by 'clang -fsanitize=address -shared-libasan', then the above
63       command might display some errors, for example:
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65       ==7625==ERROR: AddressSanitizer: heap-use-after-free on address 0x614000000044 at pc ....
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67       Without the --add-ld-preload argument, this would not work at all.
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AUTHOR

70       Written by Matthias Urlichs <smurf@noris.de>.  Modified by  Robert  Lu‐
71       berda <robert@debian.org>.
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BUGS

74       There  is  no  attempt to make this change undetectable by the program.
75       In particular, file modification times are not modified.
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77       On systems using 32-bit representation of time, datefudge  is  affected
78       by the year 2038 problem, which might cause dates to be wrapped around,
79       for instance:
80       $ TZ=UTC datefudge "2038-01-19 03:14:07" sh -c "sleep 1; date -R"
81       Fri Dec 13 20:45:53 UTC 1901
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COPYRIGHT

84       Copyright © 2003 by Matthias Urlichs.
85       Copyright © 2008-2019 by Robert Luberda.
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87       There is NO warranty; not even for MERCHANTABILITY  or  FITNESS  FOR  A
88       PARTICULAR PURPOSE.  You may redistribute copies of datefudge under the
89       terms of the GNU General Public License.
90       For more information about these matters, see the file named COPYING.
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