Job Automation / Task Sheduling.
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job/task--- an action / work
creating a process/task to run automatically on a specified time if requires
repetedly.
1.crontab
2.anacrontab
3.at job
4.batch job
1.crontab
creating a process/task to run automatically on a specified time if requires
repetedly as minutes,
hourly,daily,weekly & monthly.
output
cat /var/spool/mail/root
and
cat /var/mail/root
Deamon/Service cron.d
root user
vi /etc/crontab //for Every Job
vi /etc/cron.hourly
vi /etc/cron.daily
vi /etc/cron.weekly
vi /etc/cron.monthly
cat /etc/crontab
application user & root:
$crontab -e //to shedule
$crontab -l //to view
files are
Example 100 user's
case -1 --> 10 denied 90 allowed
vi /etc/cron.deny ----------xxxxxxxxxxx
case 2--> 90 denied 10 allowed
we have create following file then cron.deny file will be removed from status
que
vi /etc/cron.allow
special char
* Every Occurence
, Specific time
- in b/w time
/ freq time
#date
Sheduling Jobs
vi /etc/crontab //root user
00-59 00-23 01-31 01-12 0-6
min hr day_mon month day_week username cmd/script_file
c1 c2 c3 c4 c5 c6 c7
* * * * * root date
10,20 10,14,18 1-10 * 1-5 root who > /dev/pts/0
00-10 10,18 1-5 * * root lastb
*/5 */2 */2 * 1-6 root tail /etc/passwd > /dev/pts/0
00-10 10,18 1-5 * * root /code.sh
#tty //to know the terminal name
/dev/pts/0
#crontab -e
#crontab -l
00-59 00-23 01-31 01-12 0-6
min hr day_mon month day_week cmd/script_file
c1 c2 c3 c4 c5 c6
* * * * * date > /dev/pts/0
10,20 10,14,18 * * * who
00-10 10,18 1-5 * * lastb > /dev/pts/0
*/5 */2 */2 * 1-6 tail /etc/passwd
10,20 10,14,18 * * * /code.sh > /dev/pts/0
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#vi /code.sh
mkdir test
cd test
touch a b c d
echo "Hello everyone" > a
echo "Files Created"
(save the file)
666
022
----
644
----
#chmod 755 /code.sh
or
#chmod +x /code.sh
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2.anacrontab
Using this tool we can excute job skipped in crontab.
this tasks are excuted maximum once in a day.
vi /etc/anacrontab
#period in days delay in minutes job-identifier command
1 5 cron.daily nice run-parts
/etc/cron.daily
7 25 cron.weekly nice run-parts
/etc/cron.weekly
@monthly 45 cron.monthly nice run-parts
/etc/cron.monthly
1 10 cronjobs nice run-parts
/etc/crontab
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3.at job
this jobs are single run jobs.
we can shedule jobs based on time.
syn: #at <time> //24 hrs or 12 hrs
e1.#at 10:00am
at>/code.sh > /dev/pts/0
at>who
at> uptime > /dev/pts/0
at>ctrl+d //to save
#atq //to view at jobs
#atrm job_id //to remove a job
e2.#at now
at>date > /dev/pts/0
at>ctrl+d
e3.#at now +1min/hour/day/week/month //to delay job
files are
Example 50 people
case1 40 allow 10 deny
vi /etc/at.deny XXXX
case2 40 deny 10 allow
vi /etc/at.allow
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4.batch job
to excute batch job system load avg must below 0.8
#batch
at>systemctl restart network
at>ctrl+d
#atq //to view batch jobs
#atrm <job-id> //to remove jobs
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