[Gluster-devel] Small note on 'dd' and cross platform block sizes

Justin Clift justin at gluster.org
Fri Jul 11 13:32:55 UTC 2014


On 11/07/2014, at 2:30 PM, Jeff Darcy wrote:
>> On Fri, Jul 11, 2014 at 11:48:18AM +0100, Justin Clift wrote:
>>> It turns out that with the 'dd' command, the block size parameter
>>> (bs=) needs a bit of special treatment to work cross-platform.
>>> 
>>> Instead of using the 'M' suffix (eg 1M for 1MB), it's better to
>>> use the k suffix.  eg 1024k for 1MB.
>> 
>> For the sake of completeness:
>> Linux uses M for megabyte, BSD(incorrecly) uses m
>> Both use k for kilobyte. This is why 1024k is better than 1M or 1m.
> 
> Does the BSD version also support status=none to make it work
> silently instead of spewing block counts to stderr?  If not, I might
> suggest that we switch to using our own wrapper that detects the
> platform to do the appropriate uppercase/lowercase and extra
> arguments vs. shell redirection in each case.


Maybe we should 2>/dev/null ?

+ Justin

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