I am using centos and I need to find out where is the php installation path is. Is there a command I can use to find that out. Thanks
I'm not sure what you mean by install path, if you're talking about the binary 'which php' will probably work.
If you're referring to something else like the extension install dir and assuming your php was installed with RPMs, do a 'yum install php-devel' to get the php-config command. You can run it with no options to get a listing of everything it knows or you can request only certain info from it, here's some useful ones for your situation:
php-config --php-binary php-config --extension-dir php-config --include-dir
Also try running 'php -i' on the command line to get the output of phpinfo.