fileReadPos

fileReadPos(
  const handle,      // file handle
 [const newpos]);    // new position if supplied

Queries file read pointer. If a new position is given as 2nd argument, the read pointer ist moved to that position.

Examples:

var pos = fileReadPos(fh);  // query current position
fileReadPos(fh, 100);       // seek to 100
fileReadPos(fh,fileReadPos(fh)-5); // seek back 5 chars