php cronjob doesn't write to file - php

Question

i'm writing a simple php script which made some stuffs every hour and write a log file.
The issue is cronjob doesnt write to log file, is it a permission issue? is it a path issue?
I have an hosting service by siteground. Script file has permission to write, read and execute.
I've already try to set a cronjob which just send me an email without write a file and it's running.Thanks
This is my code:
//
//some stuffs here
//
$file='www.domainname.com/logfile.csv';
$handle = fopen ($file, "w");
fwrite($handle, "hello, i done some stuffs");
fclose($handle);

Answer 1

You should use the absolute or relative path to the file on the file system.
example: -
$handle = fopen( $_SERVER['DOCUMENT_ROOT'] . '/logfile.csv' );

Answer 2

Generally having a writable file in the web servers directory is a bad idea. If your program can write to the file, then the web server can write to the file too. That opens the possibility for someone to overwrite the file through the web server. At best you lose data from being over written. At worst it allows remote code execution.
It would be better to put the writable files outside the web server directory.
<Parent directory>
<Place for writable files>
<Web server directory>
In your programs run from the webserver you just need to specify the path to the files.
Relative Path
$relitivePath = '/../writeDir';
$handle = fopen( $_SERVER['DOCUMENT_ROOT'] . $relitivePath . '/logfile.csv' );
Full Path
$fullPath = '/somedir/ParentDir/writeDir'
$handle = fopen( $fullPath . '/logfile.csv' );
Running from cron a bit different than running it from shell. The environment you are use to is not set up like yo have when sshing in. Your going to have to list the full path or set up the environment.
$fullPath = '/somedir/ParentDir/writeDir'
$handle = fopen( $fullPath . '/logfile.csv' );
To get your full path
When ssh'ed in:
cd to the directory where the file located.
Do a pwd this will print the current working directory path.
Use that path in like above.
In the program it is a good idea to turn error reporting on.
You also don't want to have the program you call from cron in the web directory.
I see your service provider has a way to email any output from cron. That will help with error reporting.