问题
I need a crontab syntax which should execute a specific PHP script /var/www/html/a.php every minute. The execution on every minute must start at 00:00. The other task which must execute a script at 00:00 /var/www/html/reset.php (once every 24 hours).
回答1:
every minute:
* * * * * /path/to/php /var/www/html/a.php
every 24hours (every midnight):
0 0 * * * /path/to/php /var/www/html/reset.php
See this reference for how crontab works: http://adminschoice.com/crontab-quick-reference, and this handy tool to build cron jobx: http://www.htmlbasix.com/crontab.shtml
回答2:
This is the format of /etc/crontab:
# .---------------- 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
I recommend copy & pasting that into the top of your crontab file so that you always have the reference handy. RedHat systems are setup that way by default.
To run something every minute:
* * * * * username /var/www/html/a.php
To run something at midnight of every day:
0 0 * * * username /var/www/html/reset.php
You can either include /usr/bin/php in the command to run, or you can make the php scripts directly executable:
chmod +x file.php
Start your php file with a shebang so that your shell knows which interpreter to use:
#!/usr/bin/php
<?php
// your code here
来源：https://stackoverflow.com/questions/5398014/using-crontab-to-execute-script-every-minute-and-another-every-24-hours