Use php for linux automatic script execution. Recently, I used PHP as a community. when I wrote the code to calculate the maximum number of online users, I successfully debugged the code to run PHP directly on the server as a shellscript. when working in the community, it is often necessary to count the number of people going online. recently, PHP is used as a community. when writing to calculate the maximum number of people going online, PHP is successfully debugged and runs directly on the server as a shell script.
When working in the community, it is often necessary to count the number of online users and other data. generally, this code is stored in the user login or a page to trigger the code when the user logs on or accesses the page. in this way, a problem occurs. if the code is complicated, the normal call speed of the page is obviously slowed down.
Using this feature of PHP and the linux crontab command, you can automatically and periodically execute a php file (counting the number of online users ).
Specific method:
When installing PHP, an executable file is generated, named php. copy the file to/usr/local/bin.
Run the php program in the terminal mode: php-q onlinnum. php
Note that PHP is originally applied on a webpage, so it will certainly send the html header, but here we want to use PHP as a Shell Script, "-q" means not to send HEADER. you can try not to add the result of-q.
Now you can run the PHP code in the terminal mode.
Linux command: cron daemon
This is a resident service in the system that performs routine work, such as checking disks once a day or once a month. Cron daemon checks the scheduled worksheet (crontab) every minute to check whether there are instructions to be executed. all outputs are sent to the user by mail.
Set crontab
Command: crontab-e
This command calls the vi editor to edit the execution list. For example
& Nbs p; 0 0 ** fsck/home
& Nbs p; 1 *****/home/Gull/onlinnumber
Each row represents a scheduled task. it is a scheduled time before the command. There are a total of five columns separated by spaces, sorted from left to right as follows:
Field & nbs p; description
--------------------------
Minutes from 00 to 99
From 0 to 24 o'clock
Day & nbs p; from 01 to 31
Month & nbs p; from 01 to 12
The week ranges from 01 to 07, representing Monday to Sunday.
* Indicates "every". if it is executed every day, enter * in the third column.
So the two tasks in the above example are:
Check/home disk on the 1st and 15th of each month
Run the/home/Gull/onlinnumber file in the first hour.
View crontab: crontab-l
Delete crontab: crontab-r
Well, here, you should know how to use the PHP and crontab commands to count the number of online users?
Note:
If a database is used in php, such as oracle, you need to configure the export Oracle environment in the execution script. Because the script execution in cron is performed without logon, many environment variable values set in the system are missing, and problems may occur when connecting to the database.
When writing to the computing maximum number of online users, you can Debug PHP as a shell script and run it directly on the server. when you are working in the community, you often need to count the number of online users...
