CronJob

Example

Example: Insert a record into a database every one minute.
1. Create a .sh file
----insertsms.sh---

mysql -N -u root -e "use database; INSERT INTO table1 (project_id,feedback_id, text)VALUES (5,201,'Thank you,  I am ALWAYS happy with the service I receive from .......');"

2. Run command in the command line
# crontab -e

3.  Append the following entry:
0-59 * * * * /root/ insertsms .sh
save the file

More Examples

To run /path/to/command five minutes after midnight, every day, enter:

5 0 * * * /path/to/command

Run /path/to/script.sh at 2:15pm on the first of every month, enter:

15 14 1 * * /path/to/script.sh

Run /scripts/phpscript.php at 10 pm on weekdays, enter:

0 22 * * 1-5 /scripts/phpscript.php

Run /root/scripts/perl/perlscript.pl at 23 minutes after midnight, 2am, 4am ..., everyday, enter:

23 0-23/2 * * * /root/scripts/perl/perlscript.pl

Run /path/to/unixcommand at 5 after 4 every Sunday, enter:

5 4 * * sun /path/to/unixcommand

Field Definition

* * * * * *
| | | | | | 
| | | | | +-- Year              (range: 1900-3000)
| | | | +---- Day of the Week   (range: 1-7, 1 standing for Monday)
| | | +------ Month of the Year (range: 1-12)
| | +-------- Day of the Month  (range: 1-31)
| +---------- Hour              (range: 0-23)
+------------ Minute            (range: 0-59)

Use special string to save time

Instead of the first five fields, you can use any one of eight special strings. It will not just save your time but it will improve readability.

Special string	Meaning
@reboot	Run once, at startup.
@yearly	Run once a year, "0 0 1 1 *".
@annually	(same as @yearly)
@monthly	Run once a month, "0 0 1 * *".
@weekly	Run once a week, "0 0 * * 0".
@daily	Run once a day, "0 0 * * *".
@midnight	(same as @daily)
@hourly	Run once an hour, "0 * * * *".

Run ntpdate every hour:
@hourly /path/to/ntpdate
Make a backup everyday:
@daily /path/to/backup/script.sh