This function tests whether the client is currently at the end of the file pointed to by the given file descriptor. The only valid input is a file descriptor returned by the $open() function.
This function is used to see if the end of a file has been reached. This is mostly useful while reading a file, such that it can be closed once the end is reached.
-1 error, no such file descriptor 0 not at end of file 1 end of file reached