Shulou(Shulou.com)06/01 Report--

Unit 3: system sub-delay and timing mechanism

1pat delay

At time

At > Action

At > ctrl+d

St >

At-l

Atrm task number

When the execution action has an output, the output is sent to the initiator of the task in the form of an email

Mail

Blacklist and whitelist of at users

/ etc/at.deny # exists by default and takes effect

/ etc/at.allow # does not exist by default. Once it exists (touch / etc/at.allow, in which you can write a user name to be set as a whitelist object, so that both root and whitelist users can use the at command), / etc/at.deny is invalid, and all users except root cannot use the at command.

2, system periodic tasks

Initiated by command:

Crontab-u username-e

Minute 0-59

Hour 0-23

Day of month 1-31

Month 1-12 (or names, see below)

Day of week 0-7 (0 or 7 is Sunday, or use names)

Mm hh dd MM ww

Mm/2, every two minutes.

What time to what time is hh2-hh3?

What time and what time is hh2,hh3

Crontab-l view

Crontab-u username-r cancels periodic tasks

Crontab-e edit file

Initiated by the way of the file

Vim / etc/cron.d/filename

Mm hh dd MM ww username action

Echo'mm hh dd MM username Action'> / etc/cron.d/filename

Black and white list

Vim / etc/cron.deny

Vim / etc/cron.allow

3. Management of temporary files in the system

Vim / usr/lib/tmpfiles.d/*.conf

Type filename perm user group time

A / mnt/westos 1777 root root 10s

Systemd-tmpfiles-create / usr/lib/tmpfiles.d

Systemd-tmpfiles-clean / usr/lib/tmpfiles.d

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