Linux Learning summary task plan

Task Scheduling on Linux

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

To perform a task periodically: crontab

Email service

Smtp:simple Mail Transmission protocol

/var/spool/mail/username

Mail command

Mail: An excuse to enter interactive email

Mail-s ' subject ' [email protected]

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

Command | mail-s ' subject ' [email protected]

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AT command

A job that hosts the next time run

Support for using the default job queue

CTRL + D exit

At "option" ... time

Time

1: Absolute Time

hh:mm mmdd "CC" YY

2: Relative time

now+ Minute/hour/day/week

3: Blur Time

Midnight Noon Teatime

Common options

-q:at Job Queue

-F:/path/fuom/somefile read files to be executed from the specified file

-C: View Run job contents

-D: Delete the specified job

Batch: There is a system that chooses to run the specified task at the time of the space

Crontab: Recurring Task Schedule

Daemon: Crond

There are two types of recurring tasks:

(1) System cron task, do not run the user identity by default, so you need to specify the additional runner

/etc/crontab

# Example of Job definition:

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

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

# |  | .----------Day of Month (1-31)

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

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

# |  |  |  | |

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

7 fields:

1-5: Specify a point in time

6: Run task with that user's identity

7: The task to run

5 Time points:

Minutes: Valid value range 0-59

Hours: 0-23

Day: 1-31

Month: 1-12

Weeks: 0-7

Note: Several months and weeks cannot be used simultaneously

Time Representation Method:

*: Any time point in the valid value range for the point in time

-: Continuous range of time

,: Discrete time range

/#: Specify Frequency

(2) User Cron Task: Submitted by a user, the identity of the default submitter runs without additional designation

/var/spool/cron/username

VIM command: Not recommended

Crontab: Recommendations

crontab Command options:

-u User: Not managing your own tasks, but specifying cron tasks for target users, only for the root user

-L: List All Tasks

-R: Remove All Tasks

-E: Edit cron Task table

Note: (1) If you do not want to perform any notification messages for results

COMMAND >/dev/null

COMMAND &>/dev/null

(2) for the crontab file,% has a special function, if you need to use the escape character

(3) Crontab applicable decision Path

2, every Monday to Saturday 3:20 A.M., run the CP command to archive the/etc/directory, storage location is/BACKUPS/ETC-YYYY-MM-DD;

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

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4, every night 12 o'clock, get all the lines in the/proc/meminfo file starting with S or M, appended to the/statistics/meminfo.txt file, and the daily message before, to add a similar =============== separator line;

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Linux Learning summary task plan