php functions specific to linux...

hi all, I have to write PHP pages which are portable across Linux/windows. Can anyone give me some links where I can find list of those functions which are very much Linux specific? Regards, Abhimanyu ************************************************************************** This email (including any attachments) is intended for the sole use of the intended recipient/s and may contain material that is CONFIDENTIAL AND PRIVATE COMPANY INFORMATION. Any review or reliance by others or copying or distribution or forwarding of any or all of the contents in this message is STRICTLY PROHIBITED. If you are not the intended recipient, please contact the sender by email and delete all copies; your cooperation in this regard is appreciated. **************************************************************************