3.2.169 tell

tell FILEHANDLE
tell

This function returns the current file position (in bytes, 0-based) for FILEHANDLE. This value is typically fed to the seek function at some future time to get back to the current position. FILEHANDLE may be an expression whose value gives the name of the actual filehandle, or a reference to a filehandle object. If FILEHANDLE is omitted, the function returns the position of the file last read. File positions are only meaningful on regular files. Devices, pipes, and sockets have no file position.

See seek for an example.