Linux task management with Margo Linux (Lesson 5)

1.linxu Task Scheduler:

Task Schedule:

Perform a task at a future point in time: At,batch

Recurring tasks: crontab

e-Mail Service:

Smtp:simple Mail Transmission protocol

/var/spool/mail/username Personal Mail Buffer directory

Pop3:post Office Protocol

Imap4:internet Mail Access Protocol

Mua:mail command

Mail

Mail: Enter the interactive send and receive mail interface

Mail-s "SUBJECT" [email protected]

Mail-s "SUBJECT" [email protected] < echo "AAA"

Command | Mail-s "SUBJECT" [email protected]

AT command:

Commands to host future executions

Execute using Job queue

Default to a queue

Crtl+d

at [option].. Time

Time command:

1. Absolute time hh:mm Mmdd[cc]yy

2. Relative Time now+ time

Minut Hour day Week

3. Blur Time

Midnight Noon Teatime

Common options:

-Q queue at job queues

-f/path/filename read the developed file job from the specified file

-L View the list of running jobs in the job queue, equivalent to the ATQ command

-C At_job_num to get the details of the task to be job

-d Deletes the specified command job, equivalent to ATRM

Batch

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

Crontab: Periodic execution of Mission plans

Daemon: Crond

There are two types of recurring tasks:

(1) System cron Task: The user identity is not run by default, so you need to specify additional running

/etc/crontab

Vim command

7 fields

Top 5 fields: Time field

Username: which user to run

Command: Run the order

(2) User Cron Task: Submitted by a user, run as submitter by default

/var/spool/cron/username

Vim command:

7 fields

Top 5 fields: Time field

Username: which user to run

Command: Run the order

5 Time points:

First field minute: Domain 0-59

Second field hour: domain 0-23

Third Field Day: Range 1-31

Fourth field month: Domain 1-12

Fifth field week: Domain 0-7

Note: It is not recommended to use both days and weeks of the month

Time notation:

Number: Indicates a specific point in time

*: At each point in time valid value range

-: A continuous time range, e.g. 3-7

,: A discrete time range, such as 3,5,7

/: How many times in the effective time range, specify the frequency of execution

crontab command

crontab [-u user]-l-r-E

-u User: Not running your own cron task, only administrators have permissions

-L: List cron tasks

-r: Delete cron task

-E: Edit cron Task

Supplemental tool: Anacron check for last cron not functioning automatically

Note: If you do not want to receive messages that command run results

COMMAND >/dev/null

Commadn &>/dev/null

For crontab file% there is a special meaning to use transfer escapes

Crontab's path variable is not exactly the same as the user environment variable and requires an absolute path

Practice:

1, every Monday to Saturday 3:20 A.M., run the tar command to backup the/etc directory, the backup directory is/BACKUP/ETC-YYYY-MM-DD.TAR.XZ

2, every Sunday 2:30 A.M., run the CP command to backup the/etc/fstab command, the backup path is/BACKUP/FSTAB-YYYY-MM-DD-HH-MM-SS

3, every night 12 o'clock, get all the lines in the/proc/meminfo file starting with S or M, append to the middle of/static/meminfo.txt to =============== as the delimiter.

1.[[email protected] ~]# CRONTAB-E20 3 * * 1-6 tar-czvf/backup/etc-$ (date ' +%f '). Tar.gz/etc/2. [[email protected] ~]# CRONTAB-E30 2 * * */* cp/etc/fstab/backup/fstab-$ (date ' +%f-%h-%m-%s ') 3. [Email protected] ~]# CRONTAB-E0 * * * echo "================================================" >>/statistics/ Meminfo.txt && Cat/proc/meminfo | Grep-e ' ^s|^m ' >>/statistics/meminfo.txt

Linux task management with Margo Linux (Lesson 5)