Are you looking for a way to securely delete the sensitive data (or files) from the hard drive in Linux? If yes, then this post is for you. I want to show you the shred command in Linux that overwrite the specified file(s) to hide and delete its contents. We are very much use to of using rm command in Linux to delete the files but in the background it just breaks the link (or unlink) the data block from its index number and the content of the file remains on the hard drive which can possibly be recovered using data recovery software or hardware appliances that makes rm command insufficient when it comes to destroy the data files. shred provides a mechanism to repeatedly overwrite the data file(s) and optionally delete it in order to make it harder for even very expensive hardware probing to recover the data.
Cron is a daemon in Linux that executes scheduled commands. Cron looks for /var/spool/cron directory for crontab files which are named after user accounts in /etc/passwd file and then found crontabs are loaded into the memory. Cron also searches for /etc/crontab file and the files in the /etc/cron.d directory. On Red Hat systems, crond supports access control with PAM (Pluggable Authentication Modules). A PAM configuration file for crond is installed in /etc/pam.d/crond. Crond loads the PAM environment from the pam_env module, but these can be overridden by settings in the crontab file.