LINUX Task Scheduler Application Summary

Task Scheduler Related programs:

Perform a task at a time in the future: at, Batch

Perform a task periodically: Crontab \ \ Operations

Execution Results view: Mail

Mail e-mail Service:

Default execution result write:/var/spool/mail/username

Smtp:simple Mail Transmission protocol

/var/spool/mail/username

Pop3:post Office Protocol
Imap4:internet Mail Access Protocol1 '

Mua:mail command

Mail command:

Mail: Enter the interactive email interface;

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Mail-s ' SUBJECT ' [email protected]

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Mail-s ' SUBJECT ' [email protected] </path/from/somefile

COMMAND | Mail-s ' SUBJECT ' [email protected]

At

To host a job that runs in the future time:

Support for using job queues:

The default is a queue;

Ctrl+d Saving Tasks

At [option] ... Time

Time:

(1) Absolute time

HH:MM,

Mmdd[cc]yy,mm/dd/[cc]yy, dd.mm.[cc]yy or [cc]yy-mm-dd

Tomorrow

(2) Relative time

now+ #UNIT

Minute,hour, day, week

(3) Blur time

Midnight Midnight

Noon PM

Teatime Afternoon Tea Time

Common options:

-Q queue:at Job queue;

-f/path/from/somefile: Reads the job to be run from the specified file;

-L: View a list of such running jobs in the job queue; equivalent to using the ATQ command;

-C At_job_num: Look at the contents of the running job;

-D: Delete the specified job; equivalent to ATRM

Batch

The system chooses to run the specified task when the resource is more idle;

crontab : Recurring Task Schedule

Daemon: Crond

There are two types of recurring tasks:

(1) System cron task; There is no default running user identity, so you need to specify the additional runner;

/etc/crontab

Vim command

#Example of Job Definition:

#.----------------Minute (0-59)

#|.-------------Hour (0-23)

#| |.----------Day of Month (1-31)

#| | |.-------month (1-12) orjan,feb,mar,apr ...

#| | | |.----DAY of Week (0-6) (sunday=0 or 7) Orsun,mon,tue,wed,thu,fri,sat

#| | | | |

#* * * * * user-name command to be executed

7 fields:

Top 5 fields: Point in time

User-name: Run with User-name

Commandto be executed: To run a task

(2) User Cron Task: Submitted by a user, the default is to run as the submitter, so there is no need to specify the additional runner;

/var/spool/cron/username

VIM command; not recommended

crontab Command: Recommended

#Example of Job Definition:

#.----------------Minute (0-59)

#|.-------------Hour (0-23)

#| |.----------Day of Month (1-31)

#| | |.-------month (1-12) orjan,feb,mar,apr ...

#| | | |.----DAY of Week (0-6) (sunday=0 or 7) Orsun,mon,tue,wed,thu,fri,sat

#| | | | |

#* * * * * command to be executed

5 Time points:

Minutes: valid value range 0-59;

Hours: 0-23

Day: 1-31

Month: 1-12

Weeks: 0-7

Note: The date of the month and the number of weeks, not recommended to use at the same time;

Time notation:

*: Each time point in the valid value range of the time point;

-: A specific continuous time range, 3-7

,: A discrete point in time, 3,5,7

/#: The amount of time in a valid time frame, for specifying the frequency;

1-30/4,*/4

5*/3 * * */bin/echo "howdy"

* * 1-5/bin/echo "Howdy"

crontab command:

Crontab[-u user] [-l |-r |-e]

-uuser: Instead of managing its own cron task, it is the cron task of the specified target user; only Root has permission to manage other users ' cron tasks; By default it manages its own;

-l:list, list the tasks;

-r:remove to remove all tasks;

-e:edit, edit, open a default editor for the current shell session to edit the cron task table;

Practice

Every Monday to Saturday 3:20 A.M., run the CP command to save the/etc/directory for archiving, the storage location is/BACKUPS/ETC-YYYY-MM-DD

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Every Sunday 2:30 A.M., run the CP command to back up the/etc/fstab file with a storage location of/BACKUP/FSTAB-YYYY-MM-DD-HH-MM-SS

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Every night 12 o'clock, get all lines in the/proc/meminfo file that begin with S or M, append to the/statistics/meminfo.txt file, and precede the daily message with a similar =============== separator line;

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LINUX Task Scheduler Application Summary