Linux + thinkphp + gd verification code cannot be displayed

Linux + thinkphp + gd verification code cannot be displayed. the thinkphp + gd verification code can be normally displayed on the window xampp. on ubuntu12.04, you can use apt-get to install Apache2 + php2 + gd and cannot display the verification code.

Reply to discussion (solution)

This is obviously not a code issue, but a configuration issue.
Check whether the service works properly one by one.

Output phpinfo to see if all of them are normal and the permissions have been correctly granted?

Call ???? What are there ???.
In the most? Join

Ini_set ('display _ errors ', 'on'); error_reporting (E_ALL );

Yes. The path is incorrect.