From 'man cdrecord'
Code:
blank=type
Blank a CD-RW and exit or blank a CD-RW before writing. The
blanking type may be one of:
help Display a list of possible blanking types.
all Blank the entire disk. This may take a long time.
fast Minimally blank the disk. This results in erasing
the PMA, the TOC and the pregap.
track Blank a track.
unreserve Unreserve a reserved track.
trtail Blank the tail of a track.
unclose Unclose last session.
session Blank the last session.
Not all drives support all blanking types. It may be necessary to use
blank=all if a drive reports a specified command as being invalid. If
used together with the -force flag, this option may be used to blank
CD-RW disks that otherwise cannot be blanked. Note that you may need
to specify blank=all because some drives will not continue with cer-
tain types of bad CD-RW disks. Note also that cdrecord does it’s best
if the -force flag is used but it finally depends on the drive’s
firmware whether the blanking operation will succeed or not.
So (blank the entire CD quickly); cdrecord <the CD device here> blank=fast
And for writing an entire directory, see 'man mkisofs' and;
http://www.tldp.org/HOWTO/CD-Writing-HOWTO.html