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What are the error messages that dd outputs? I tried to look at manual, but it does not say anything about it. Or I do not know how to look at manuals (man).

Edit: OK. I'll make it simple: what error is produced to terminal if dd encounters bad block/sectors causing read error? Does it just print no error message?

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marked as duplicate by slhck Jul 22 '13 at 9:45

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Why do you need to know? What actual problem are you trying to solve? All your questions revolve around the same thing – maybe just tell us what you are really up to? – slhck Jul 22 '13 at 9:37
@slhck I edited my question. – dding Jul 22 '13 at 9:43
That's no different than your previous question. What I meant was, why do you have so many questions about dd? What do you need to do with it since you're asking so many specific questions? If you give more context about what you really need (e.g. you need to write some kind of script), you will get better answers. – slhck Jul 22 '13 at 9:47
@slhck I just ran dd without conv=sync,noerror when backing up hard disk so I am worrying that things might be missing from the outoput file (which would mean size difference) because of hard disk's bad sectors that might have been there causing read error. That's why I am wondering if dd notifies me of these types of errors, because I didn't see any error. – dding Jul 22 '13 at 10:02
I see. However in that case, having one question about that one problem you're facing is more than enough. Please refrain from creating additional ones in that direction. Thank you. – slhck Jul 22 '13 at 10:07

It would be quite time-consuming to compile a comprehensive list. If you're really interested, you could try looking at dd's source code. Try searching for 'error (' (although that's not guaranteed to get everything, it'll give you a flavour of what dd might say in the event of unpleasantness).

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