Urgent Help Needed: Corrupted files!

FatGuy · 04-15-2015, 10:02 PM

On my Mac Mini running Yosemite 'Disk Utility' is telling me that the Mac's internal HDD is faulty and needs to be replaced and that's fine because I'll buy a new HDD, BUT I need to copy off some important .PDF files from the Mac's internal HDD and I've been doing this using a new external USB HDD, but I was just reading that when a Mac's internal HDD becomes faulty it's very likely that the files on it are corrupted.

I'm VERY worried that my .PDF files(which are ebooks) have been corrupted and that when I try to read them the .PDF files will be altered in such a way that I get the completely wrong impression and the wrong understanding from the .PDF files. What can I do to check that the .PDF files haven't been altered?

Thank you for any help!

PeterT · 04-15-2015, 10:05 PM

Just try opening them with a PDF viewer. Most (if not all) data files made by application contain internal integrity checks and if their associated application detects corruption they will let you know.

cromag · 04-15-2015, 10:22 PM

PeterT's right.

It's very unlikely that your PDFs would be so subtly corrupted that you could still open them but have the meaning of the content changed, if that's what you're worried about. Corrupted PDFs will either not open, or be (very) visibly damaged.

FatGuy · 04-15-2015, 11:26 PM

Quote:

Originally Posted by cromag

It's very unlikely that your PDFs would be so subtly corrupted that you could still open them but have the meaning of the content changed, if that's what you're worried about.

Right, this is exactly what I'm worried about! Since these ebook .PDF files are a large portion of my ebook collection, I'm SUPER worried about getting the wrong impression about a particular subject because the .PDF files are corrupted.

PeterT · 04-15-2015, 11:40 PM

Seriously; if they will open with a PDF viewer they'll be fine.

Additionally, if they're that important, you do have backups of them all.

FatGuy · 04-16-2015, 12:11 AM

Quote:

Originally Posted by PeterT

Seriously; if they will open with a PDF viewer they'll be fine.

Additionally, if they're that important, you do have backups of them all.

Thanks, but this is the only copy I've got of these .PDF files... that's why I'm so worried about these .PDF files becoming modified in such a way that I get the wrong understanding when I read them.

Turtle91 · 04-16-2015, 12:14 AM

Like they said...if you can open them at all...they will be fine. OR it will be very obvious that they are corrupted....you won't be able to read anything.

Welcome to the world of those who learn the hard way to make back-ups of everything....It is a very big club.

eschwartz · 04-16-2015, 12:15 AM

Well, don't worry

Corruption is never organized enough to undetectably change the content -- that takes intentional modification. Your hard drive does not have the capability to be malicious, only people can do that...

If the PDFs contain random gibberish, they have been corrupted. If the PDF reader says "I can't open these PDFs because they are horribly corrupted", they have been corrupted.
Otherwise, they are good.

FatGuy · 04-16-2015, 12:29 AM

Thanks so much for putting my fears at ease a little.

So when I restore these ebooks which are mostly .PDF files, what's the best way for me to make sure that they haven't been altered in such a way to give me the wrong impression of a particular subject? What's the best .PDF viewer app I can use to check that they haven't been altered?

eschwartz · 04-16-2015, 12:33 AM

Literally any of them. If it opens and you can read it, you are good.

amazon author · 04-16-2015, 12:46 AM

If PDF files get corrupted you will not be able to view them.

FatGuy · 04-16-2015, 01:44 AM

Thanks a lot guys.

If anyone knows of a way I can do a scan and be 100% certain that the .PDF files are 100% fine, I'd really appreciate it!

murg · 04-16-2015, 01:55 AM

Quote:

Originally Posted by eschwartz

Your hard drive does not have the capability to be malicious, only people can do that...

You haven't met some of my hard drives...

FatGuy · 04-16-2015, 02:01 AM

Quote:

Originally Posted by murg

You haven't met some of my hard drives...

Wow, reading this has really spiked my fears... What do you mean by this?

shalym · 04-16-2015, 07:31 AM

Quote:

Originally Posted by FatGuy

Wow, reading this has really spiked my fears... What do you mean by this?

It was a joke.

With regards to your original question, though...As pretty much everyone in this thread has said, If you can open and read your PDF, then it is fine. It is NOT POSSIBLE for a failing hard drive to make subtle changes to a file like the ones that you are afraid of. Either the file is readable, or not.

Your hard drive failing can NOT change specific words in the text in a way that will change the meaning of what you are reading.

Shari

04-15-2015, 10:02 PM	#1
FatGuy Groupie Posts: 158 Karma: 1804362 Join Date: Nov 2014 Device: iPad Mini 3	Urgent Help Needed: Corrupted files! On my Mac Mini running Yosemite 'Disk Utility' is telling me that the Mac's internal HDD is faulty and needs to be replaced and that's fine because I'll buy a new HDD, BUT I need to copy off some important .PDF files from the Mac's internal HDD and I've been doing this using a new external USB HDD, but I was just reading that when a Mac's internal HDD becomes faulty it's very likely that the files on it are corrupted. I'm VERY worried that my .PDF files(which are ebooks) have been corrupted and that when I try to read them the .PDF files will be altered in such a way that I get the completely wrong impression and the wrong understanding from the .PDF files. What can I do to check that the .PDF files haven't been altered? Thank you for any help!

04-16-2015, 01:44 AM	#12
FatGuy Groupie Posts: 158 Karma: 1804362 Join Date: Nov 2014 Device: iPad Mini 3	Thanks a lot guys. If anyone knows of a way I can do a scan and be 100% certain that the .PDF files are 100% fine, I'd really appreciate it! Last edited by FatGuy; 04-16-2015 at 01:46 AM.

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04-15-2015, 10:05 PM	#2
PeterT Grand Sorcerer Posts: 13,515 Karma: 78910202 Join Date: Nov 2007 Location: Toronto Device: Libra H2O, Libra Colour	Just try opening them with a PDF viewer. Most (if not all) data files made by application contain internal integrity checks and if their associated application detects corruption they will let you know.

04-15-2015, 10:22 PM	#3
cromag Surfin the alpha waves ~~ Posts: 26,290 Karma: 459765791 Join Date: Dec 2010 Location: New Jersey Device: Jetbook Lite & Mini, Nook STR, Kobo, Hanvon N516, Kindle 2, Androids	PeterT's right. It's very unlikely that your PDFs would be so subtly corrupted that you could still open them but have the meaning of the content changed, if that's what you're worried about. Corrupted PDFs will either not open, or be (very) visibly damaged.

04-15-2015, 11:40 PM	#5
PeterT Grand Sorcerer Posts: 13,515 Karma: 78910202 Join Date: Nov 2007 Location: Toronto Device: Libra H2O, Libra Colour	Seriously; if they will open with a PDF viewer they'll be fine. Additionally, if they're that important, you do have backups of them all.

04-16-2015, 12:14 AM	#7
Turtle91 A Hairy Wizard Posts: 3,353 Karma: 20171571 Join Date: Dec 2012 Location: Charleston, SC today Device: iPhone 15/11/X/6/iPad 1,2,Air & Air Pro/Surface Pro/Kindle PW & Fire	Like they said...if you can open them at all...they will be fine. OR it will be very obvious that they are corrupted....you won't be able to read anything. Welcome to the world of those who learn the hard way to make back-ups of everything....It is a very big club.

04-16-2015, 12:15 AM	#8
eschwartz Ex-Helpdesk Junkie Posts: 19,421 Karma: 85400180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	Well, don't worry Corruption is never organized enough to undetectably change the content -- that takes intentional modification. Your hard drive does not have the capability to be malicious, only people can do that... If the PDFs contain random gibberish, they have been corrupted. If the PDF reader says "I can't open these PDFs because they are horribly corrupted", they have been corrupted. Otherwise, they are good.

04-16-2015, 12:29 AM	#9
FatGuy Groupie Posts: 158 Karma: 1804362 Join Date: Nov 2014 Device: iPad Mini 3	Thanks so much for putting my fears at ease a little. So when I restore these ebooks which are mostly .PDF files, what's the best way for me to make sure that they haven't been altered in such a way to give me the wrong impression of a particular subject? What's the best .PDF viewer app I can use to check that they haven't been altered?

04-16-2015, 12:33 AM	#10
eschwartz Ex-Helpdesk Junkie Posts: 19,421 Karma: 85400180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	Literally any of them. If it opens and you can read it, you are good.

04-16-2015, 12:46 AM	#11
amazon author Cracking Coding Interview Posts: 33 Karma: 10 Join Date: Mar 2015 Device: iPhone	If PDF files get corrupted you will not be able to view them.