svn commit: r187609 - head/bin/dd

Giorgos Keramidas keramida at
Thu Jan 22 19:46:45 PST 2009

Author: keramida (doc committer)
Date: Fri Jan 23 03:46:44 2009
New Revision: 187609

  Add an example of using bs=2048 to duplicate data CD-ROMs.
  This should be a bit useful for users who look at the manpage and
  then try to copy data CD-ROM disks using dd.  A lot of us know
  that bs=2048 is required, but it still manages to cause a bit of
  grief to those who haven't heard about it.
  PR:		bin/130857
  Submitted by:	Tri Brotoharsono < mail at >
  MFC after:	3 days


Modified: head/bin/dd/dd.1
--- head/bin/dd/dd.1	Fri Jan 23 03:15:28 2009	(r187608)
+++ head/bin/dd/dd.1	Fri Jan 23 03:46:44 2009	(r187609)
@@ -392,6 +392,11 @@ Remove parity bit from a file:
 Check for (even) parity errors on a file:
 .Dl "dd if=file conv=pareven | cmp -x - file"
+To create an image of a Mode-1 CD-ROM, which is a commonly used format
+for data CD-ROM disks, use a block size of 2048 bytes:
+.Dl "dd if=/dev/acd0 of=filename.iso bs=2048"
 .Xr cp 1 ,
 .Xr mt 1 ,

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