[arch-general] Replace dcron once again?
vcappe at gmail.com
Sat Nov 13 18:57:01 CET 2010
Allan McRae <allan at archlinux.org> wrote:
> Surely someone can run a git bisect on this issue. It is a reasonably
> new occurrence.
Except that the @daily bug only trigger every 24 hours or so. A little
too time consuming for git bisect, i would say.
But, there is a way around this: overriding the libc time() and
localtime() functions with LD_PRELOAD to trick crond into thinking
time passes quicker than it actually do. libfaketime can do
this. So you can launch crond with something like this (as root):
# faketime -f '+0 x30'./crond -s /tmp/systabs -c /tmp/usertabs -t /tmp/stamps -d
which will make @hourly happen about every two minutess and @daily about
every 48 minutes. note: using x60 and above will utterly confuse crond
(Not a Bug), so don't do that.
Combine with a crontab like this:
@hourly ID=hourly echo "HOURLY $(date)" >> /tmp/dcron-test
@daily ID=daily echo "DAILY $(date)" >> /tmp/dcron-test
@weekly ID=weekly echo "WEEKLY $(date)" >> /tmp/dcron-test
@monthly ID=monthly echo "MONTHLY $(date)" >> /tmp/dcron-test
You can then monitor /tmp/dcron-test and see if jobs are scheduled
Also the TZ environment variable can be useful (see 'info libc tz').
But, i was not able to reproduce the "@hourly run only once every
two hours" problem with neither TZ=FOO-1BAR-2,N10,N350 , nor
'export TZ=:/usr/share/zoneinfo/Europe/Paris; faketime -f -60d ./crond ... -d'.
So, it seems DST alone is not enough to trigger it. Presumably, it
also depends upon the content of the timestamp files ?
I never saw the @daily bug, personally.
Sent thru gmane, let's see if it works.
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