cron command to run every 12 hours

A crontab file has five fields for specifying day , date and time followed by the command to be run at that interval.

*     *     *   *    *        command to be executed-     -     -   -    -|     |     |   |    ||     |     |   |    +----- day of week (0 - 6) (Sunday=0)|     |     |   +------- month (1 - 12)|     |     +--------- day of        month (1 - 31)|     +----------- hour (0 - 23)+------------- min (0 - 59)

* in the value field above means all legal values as in braces for that column.

You could use 0 1,13 * * * which means for every 1AM and 1PM.

0 1,13 * * * rm /var/www/*/somedir/index.php > /home/someuser/cronlogs/some.log 2>&1

where * can be replaced by different domain names.

I think the right way is -> 1 */12 * * * (actually, any number in the minute position will do the trick.)

If you set -> * */12 * * * it will be executed every minute at 12h and again at 24h.

Assuming your sites live in /var/www/sitename and you have the php shell installed in /usr/bin/php you can easily create a cron job that runs all those files.

run

crontab -e

and add this line

42 */12 * * * /usr/bin/php /var/www/*/somedir/index.php  >> ~/cronjob.log 2>&1

The * here in /var/www/*/somedir is just a wildcart. This means it will catch every directory in your /var/ww folder.

f.ex:

[jens@localhost ~]$ ls -l temptotal 28-rw-rw-r--. 1 jens jens 1641 Feb 21 16:12 somefile.pydrwxrwxr-x. 2 jens jens 4096 Feb 22 15:10 testdrwxrwxr-x. 2 jens jens 4096 Feb 22 15:10 test2drwxrwxr-x. 2 jens jens 4096 Feb 22 15:10 test3drwxr-xr-x. 8 jens jens 4096 Jan 27 10:21 emptydir-rw-rw-r--. 1 jens jens  548 Jan 27 16:15 Unsaved Document 1[jens@localhost ~]$ ls temp/*/testfile.php temp/test2/testfile.php  temp/test3/testfile.php  temp/test/testfile.php

As you can see, this returns the testfile.php in each subfolder of temp, namely folder test, test2 and test3. Emptydir is also a folder, but since it has no testfile.php in it, nothing willhappen with it.