Para o Debian (e derivados) com o systemd:
Você pode, por exemplo, examinar /var/log/syslog
. Assim:
sudo grep -i 'cron' /var/log/syslog
Além disso, para verificar o status atual do daemon do cron, você pode fazer:
sudo systemctl status cron
O que lhe dará uma saída assim:
● cron.service - Regular background program processing daemon
Loaded: loaded (/lib/systemd/system/cron.service; enabled)
Active: active (running) since mon 2016-08-22 09:02:16 CEST; 1 months 5 days ago
Docs: man:cron(8)
Main PID: 570 (cron)
CGroup: /system.slice/cron.service
└─570 /usr/sbin/cron -f
sep 27 07:09:01 server CRON[24945]: (root) CMD ( [ -x /usr/lib/php5/s...)
sep 27 07:09:01 server CRON[24944]: pam_unix(cron:session): session cl...t
sep 27 07:17:01 server CRON[24984]: pam_unix(cron:session): session op...)
sep 27 07:17:01 server CRON[24985]: (root) CMD ( cd / && run-parts -...)
sep 27 07:17:01 server CRON[24984]: pam_unix(cron:session): session cl...t
sep 27 07:30:01 server CRON[24989]: pam_unix(cron:session): session op...)
sep 27 07:30:01 server CRON[24990]: (root) CMD (test -x /etc/init.d/an...)
sep 27 07:39:01 server CRON[25234]: pam_unix(cron:session): session op...)
sep 27 07:39:01 server CRON[25235]: (root) CMD ( [ -x /usr/lib/php5/s...)
sep 27 07:39:01 server CRON[25234]: pam_unix(cron:session): session cl...t
Hint: Some lines were ellipsized, use -l to show in full.