tell
Returns the current byte position in a filehandle.
Returns the current read/write position (in bytes) for the given filehandle, or for the most recently read filehandle when called without arguments. Returns -1 on error or when no filehandle is available.
The returned value is suitable as the POSITION argument to seek.
Synopsis
$pos = tell($fh); # position in $fh
$pos = tell(); # position in last-read filehandle