how to open, read, and close a file on the server.

PHP File Open - Read - Close

Modes	Description
r	-> Open a file for read only. File pointer starts at the beginning of the file
w	-> Open a file for write only. Erases the contents of the file or creates a new file if it doesn't exist. File pointer starts at the beginning of the file
a	-> Open a file for write only. The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn't exist
x	-> Creates a new file for write only. Returns FALSE and an error if file already exists
r+	-> Open a file for read/write. File pointer starts at the beginning of the file
w+	-> Open a file for read/write. Erases the contents of the file or creates a new file if it doesn't exist. File pointer starts at the beginning of the file
a+	-> Open a file for read/write. The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn't exist
x+	-> Creates a new file for read/write. Returns FALSE and an error if file already exists