Function fdTruncate (fd,size:longint) : boolean;
fdTruncate sets the length of a file in fd on size bytes, where size must be less than or equal to the current length of the file in fd.
The function returns True if the call was successful, false if an error occurred.
Errors are returned in LinuxError.
fdOpen, fdClose, fdRead,fdWrite,fdFlush, fdSeek