System scheduled tasks and delayed tasks

Delayed task

Eg: leave temporarily and let it postpone shutdown

Write the script in advance and let it be executed

# # 1. Deferral task initiation # experiment: monitoring: the effect is obvious watch-n 1 ls-lR / mnt and then initiate a deferred task in enterprise 8: note above

# 2. When the deferred task has output, the output will be emailed to the task initiator's mailbox # dnf whatprovides / bin/maildnf install mailx-12.5-29.el8.x86_64 postfix: Mail service installs this service dnf install postfix-y

Q: exit

# 3.at command control # # / etc/at.deny at control blacklist people on this list cannot execute at/etc/at.allow 1. This file does not exist by default, * * 2. When this file exists / etc/at.deny does not take effect * * 3. When this file exists in the system, ordinary users cannot execute at by default, but only users in the list can execute it.

Note: 3.2

Scheduled task

Eg: alarm clock

-u user

-e editor

Man 5 crontab to view the corresponding representation