Safe mode is a diagnostic mode of a computer operating system (OS). It can also refer to a mode of operation by application software. Safe mode is intended to fix most, if not all problems within an operating system. It is also widely used for removing Rogue security software.

The PHP safe mode is an attempt to solve the shared-server security problem. It is architecturally incorrect to try to solve this problem at the PHP level, but since the alternatives at the web server and OS levels aren’t very realistic, many people, especially ISP’s, use safe mode for now.

• Limit the execution of shell commands
• Limit access to system environment variables
• Limit the paths from which PHP can include files using include or require