Why can cronjob and systemd not work together?

variable

6/15/23, 7:50 PM

I want to auto renew the certbot certificate. I came across the following auto generated file but it says:

This cronjob will NOT be executed if you are running systemd as your init system.

I am using systemd for automatically restarting some other services in case of crash/system restart. So I'm assuming that above quote applies to me.

What is the reason that the cronjob won't run when systemd is used as the init system? Can systemd and cronjob not be used together?

# /etc/cron.d/certbot: crontab entries for the certbot package
#
# Upstream recommends attempting renewal twice a day
#
# Eventually, this will be an opportunity to validate certificates
# haven't been revoked, etc.  Renewal will only occur if expiration
# is within 30 days.
#
# Important Note!  This cronjob will NOT be executed if you are
# running systemd as your init system.  If you are running systemd,
# the cronjob.timer function takes precedence over this cronjob.  For
# more details, see the systemd.timer manpage, or use systemctl show
# certbot.timer.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(43200))' && certbot -q renew

0 + 0

cron

systemd

20.04

steeldriver

6/15/23, 9:26 PM

It looks like it is *designed* not to run if systemd is the init system (the test `! -d /run/systemd/system` will fail) - presumably because the cron job is unnecessary in that case

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Why can cronjob and systemd not work together?

TH: เหตุใด cronjob และ systemd จึงทำงานร่วมกันไม่ได้

RO: De ce pot cronjob și systemd să nu funcționeze împreună?

RU: Почему cronjob и systemd не могут работать вместе?

VI: Tại sao cronjob và systemd không thể hoạt động cùng nhau?

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