Day Fifth: Linux Scheduled Tasks

Mail command:

Send and receive mail (mua:mail user agent to send and receive mail)

Use the command:

Mail-s ' Subject ' [email protected]

Enter after entering the interactive input interface, after entering the message content. Enter to end the message entry, the message content can be entered redirect to Mail, the command execution results are sent to the user by mail.

At: Perform a task at once.

How to use:

• at [Opption] ... time

Time Format:

• HH:MM[YYYY-MM-DD]

• Noon,midnight,teatime,tomorrow,now + # (Min,h,days,weeks)

Common options:

• -L View Job queue, equivalent to ATQ

• -F reads the configuration file from the file into the queue and puts all the tasks at the at to the file, allowing at to read the file as a running task. Example: At-f/path/to/file

• -d deletes the specified queue job, which is equivalent to the ATRM command, and can cancel a job that is queued at the at schedule

• -C View specific contents of the specified job

• -V You can use the more obvious time format to list the work lists in at.

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System cron: The system task is implemented by editing the configuration file/etc/crontab.

User cron: Configuration file saved at/var/spool/cron/$USERNAME

How to use:

• -L: Lists scheduled tasks that have already been defined (essentially viewing the contents of the configuration file)

• -E: Define scheduled Tasks through the Vim editor and automatically format checks when you save exits

• -r: Remove all scheduled Task information

• -I: Two acknowledgements when using the-r option.

Scheduled Task writing format:

# 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 (username) command to be executed (command best use absolute path, plus option)

Attach common time Get format: Date +\%y\%m\%d\%h\%m (precision to minutes)

Homework:

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;
* * 1-6/usr/bin/cp/etc/backup/etc-$ (date +\%y-\%m-\%d) 2>/val/log/backup_log 1>/dev/null
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;
2 * * 7/usr/bin/cp/etc/fstab/backup/fstab-$ (date +%y-%m-%d-%h-%m-%s)
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 before the daily message,
To add a similar =============== separation line;
0 0 * * */bin/grep ' ^s\|^m '/proc/meminfo >>/statistics/meminfo.txt; /bin/echo "==========" >>/statistics/meminfo.txt

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This article from "11243775" blog, declined reprint!

Day Fifth: Linux Scheduled Tasks