Setting up Cron job using PHP script [duplicate] - php

Question

This question already has answers here:
PHP parse/syntax errors; and how to solve them
(20 answers)
Closed 7 years ago.
I am beginner in programming and I was trying to set up Cron Job using PHP script in couple ways, which I found on the internet, but I always run into some errors I can't fix by myself:
First method:
exec('echo -e "`crontab -l`* * {$_POST['birthDay']} {$_POST['birthMonth']} * /home/jharvard/vhosts/pset7/public/{$_POST['lastname']}{$_POST['firstname']}.php" | crontab -");
,but I think error appears because of ` symbol and I am sure a lot of ' symbols os not good either.
Second method:
echo "* * {$_POST['birthDay']} {$_POST['birthMonth']} * /home/jharvard/vhosts/pset7/public/{$_POST['lastname']}{$_POST['firstname']}.php" | tee -a /var/spool/cron/root
Error is: ( ! ) Parse error: syntax error, unexpected 'var' (T_VAR) in /home/jharvard/vhosts/pset7/public/calendar.php on line 24
Third try:
$cron_file = "{$_POST['lastname']}{$_POST['firstname']}";
// Create the file
touch($cron_file);
// Make it writable
chmod($cron_file, 0777);
// Save the cron
file_put_contents($cron_file, "* * {$_POST['birthDay']} {$_POST['birthMonth']} * /home/jharvard/vhosts/pset7/public/{$_POST['lastname']}{$_POST['firstname']}.php");
//Install the cron
exec('crontab cron_file');
I have no idea why this one doesn't work. I execute
crontab -l
, but it doesn't show any new jobs

Answer 1

Your first try got lots of problem:
The string has started with single quotation, ended with double.
variables inside strings that started with double quote will be parsed. so if you start your string with single quote, variable won't replace with their values.
you can not use single quote character within a string started with single quote, unless you escape with backslash. (same apply to double quote as well) example: $var = '\'test\''
So grammatically, your first try should be like this:
exec("echo -e \"`crontab -l`* * {$post['birthDay']} {$post['birthMonth']} * /home/jharvard/vhosts/pset7/public/{$post['lastname']}{$post['firstname']}.php\" | crontab -");
Better Solution
As I understand from your code, you want to do something on user's birthday.
A better solution is create one single cronjob manually, that will run one file every night, and that file will manage what to do (including who's birthday is that, sending them email, etc) instead of having a cronjob for every user.

Answer 2

You can do it like this
$command = " * * * * * php PATH_TO_YOUR/some.php ";
exec('echo -e "`crontab -l`\n'.$command.'" | crontab -', $result);
var_dump($result);
by this you can add to www-data's user crontab new command, which will run some.php every minute
for more information here is reference about crontab - http://www.adminschoice.com/crontab-quick-reference , you need to read it to understand what to do with * * * * * (which are responsible for cronjob running time) and how to build correct $command with usage of php,sh and other scripts