Delay and timing mechanism

# # # #1. At delay # #

At time

At> Action

At>ctrl +d

At> <EOT>

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At now+ time , can also indicate a delay task

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At-l

ATRM Task Number

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When an action is executed with output

The output is sent as a message to the person's initiator

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at user's black and white list

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

/etc/at.allow # # default does not exist, once present,/etc/at.deny Invalid

Blacklist:

Studnet users can use the AT command before the blacklist is modified

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Modify Configuration

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After modifying the configuration file

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White list:

Modify the configuration file, add the student in the configuration file , and then you can use the at command

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# # # #2. Recurring Tasks ####

Command mode initiated:

Crontab-u USERNAME-E

MM HH dd mm WW

MM/2 # # every 2 minutes

HH1-HH2 # # How many points to how many points

HH1,HH2 # # How many points and how many points

Configuration file Modification Content

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Effect

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Crontab-l

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Crontab-u Username-r

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The way the file originated

Vim/etc/cron.d/filename

mm HH dd mm WW USERNAME Action

echo ' mm HH dd MM WW USERNAME Action ' >/etc/cron.d/filename

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Black and white list

/etc/cron.deny

/etc/cron.allow (Black and white list and time-lapse black-and-white list usage basically no difference)

# # # #3. management of temporary system files ####

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

type filename Perm User Group Time

D/mnt/westos 1777 root Root 10s

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

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

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Delay and timing mechanism