Detailed explanation of scheduled tasks and delayed tasks under Linux

at 17:23 
at> touch /mnt/file{1..9} ##Delay action at> Type ctrl+d ##Initiate action at -l | atq ##View current task at -d | atrm ##Cancel specified task at -c ##View task content at now+1min ##Delay for one minute at -f file ##Delay execution of the contents in the file at -m ##Send email to the executor when the delay command has no output at -M ##Send email to the executor when the delay command has output 

/etc/at.deny ##User blacklist. Users in this list cannot execute at commands. /etc/at.allow ##User whitelist. The list does not exist by default. But once the list appears, the blacklist becomes invalid. All users in the system cannot execute at by default. Only users in the list can use at commands.

crontab -u username -e ##Edit crontab work content crontab -u username -r ##Remove all crontab work content crontab -u username -l ##Query crontab work content 

vim /etc/cron.d/filename ##Edit this file content minute hour day month week user action * * * * * root rm -fr /mnt/* #Super user cleans up /mnt every minute 

/etc/cron.deny ##User blacklist. Users who appear in this list cannot execute crontab commands. /etc/cron.allow ##User whitelist. The list does not exist by default, but once the list appears, the blacklist becomes invalid. By default, all system users cannot execute crontab. Only users who appear in the list can use it.

vim /usr/lib/tmpfiles.d/*.conf ##Configuration file type of temporary files in the system File name File permissions File owner File all groups File existence time d /mnt/westos 777 root root 10s 
 
systemd-tmpfiles –create /usr/lib/tmpfiles.d/* ##Execute temporary file configuration vim /usr/lib/tmpfiles.d/test.conf 
systemd-tmpfiles –clean /usr/lib/tmpfiles.d/* ##Clean temporary files