Today, when I logged in and checked the ps output, I noticeda few lines that were run automatically under the root.I grepped the relevant lines here:root      1126  0.0  0.0   2616   424 ?        Ss   Apr16   0:06 cronroot      6445  0.0  0.0   2400   868 ?        Ss   07:30   0:00 anacron -sroot      6566  0.0  0.0   2244   276 ?        S    07:35   0:00 /bin/sh -c nice run-parts --report /etc/cron.dailyroot      6567  0.0  0.0   2152   524 ?        SN   07:35   0:00 run-parts --report /etc/cron.dailyroot      6574  0.0  0.0   2244   556 ?        SN   07:35   0:00 /bin/sh /etc/cron.daily/aptroot      6615  0.0  0.0   2160   272 ?        SN   07:35   0:00 sleep 1721I haven't been using cron on this machine for a long time (years), so don't remember I started it on the 16th April. What is the meaning of those commands in sequence? Could it be a security issue?
What does /bin/sh -c nice run-parts --report /etc/cron.daily mean?
shell;security;cron;nice;sleep
You may not personally be using cron, but the system uses it for essential maintenance tasks, such as rotating log files that have grown too big or too old, checking disk quotas, doing consistency checks, making sure permissions on essential files are correct, or mailing the root user differences between important configuration files that have changed since last run (this differs a lot between systems).Never try to disable cron.  It will prevent essential tasks from running on your system.If you look in /etc/cron.daily you will find all the system maintenance tasks that are run on a daily basis.  On some systems there is also a corresponding weekly and/or monthly lists of tasks.anacron is a program that is often used on machines that aren't up and running all the time.  It is likely that your system uses it to schedule the daily tasks (possibly via cron). It makes sure that daily tasks are run at least once daily (whereas cron requires the machine to be up and running at specific times to run tasks).run-parts is a Linux thing that runs multiple scripts in a directory in sequence (e.g. all scripts in /etc/cron.daily)./etc/cron.daily/apt is the currently running maintenance task, obviously having something to do with your package manager apt (possibly doing some update of either packages or of the list of available security updates or something similar).The sleep may be a delay before the next task is run, if it is related at all.In short: nothing to worry about, but do have a look at those things in /etc/cron.daily just to inform yourself about how your system works.