telldir
See the current Perl documentation for telldir.
Here is our local, out-dated (pre-5.6) version:
telldir - get current seekpointer on a directory handle
telldir DIRHANDLE
Returns the current position of the readdir() routines on DIRHANDLE. Value may be given to seekdir() to access a particular location in a directory. Has the same caveats about possible directory compaction as the corresponding system library routine.