Comparing copies of big binary files?

[toke lahti]

Is there a simple good app for this?
Meaning a real simple GUI, so that there's no need to write notes and google for an hour, when you use it once a year?
Not something like most, like Apple's Filemerge: hogging all RAM and then crashing a whole system.

Let's say I want to compare a copied 6GB iso image.
Meaning to verify that the copy isn't corrupted.

What really works?
Real experience?

Please, no discussion about how this is not needed, let's assume that it is.
I can send corrupted dmg's to those who doesn't believe they exist.

 

[chabig]

Search the App Store for "hash". There you will find many free utilities to hash any file. If the hash for two files is the same, the files are identical.

 

[hwojtek]

Let's say I want to compare a copied 6GB iso image.
Meaning to verify that the copy isn't corrupted.

HexFiend works for me. Open two files, select "compare file1 vs file2", done. There's a terminal command available as well.

Search the App Store for "hash". There you will find many free utilities to hash any file. If the hash for two files is the same, the files are identical.

This is an even faster option and it's built into the system. Open Terminal and
shasum -a 256 [path_to_file_1] (or just drag and drop file onto Terminal window), press enter.
then (or in another Terminal window/tab)
shasum -a 256 [path_to_file_2] (ditto)
If both hashes are identical, both files are identical, job done.

 

[chabig]

This is an even faster option and it's built into the system.

Yes you are right. I went to the App Store because the OP asked for a GUI.

 

[toke lahti]

Quickhash-GUI - free, cross platform data hashing tool

The homepage of Quickhash-GUI. The free, cross platform, data hashing tool of text, files and other data for Windows, Linux and Apple Mac OSX

www.quickhash-gui.org

Seems to work, not sure how fast it was.
(EDIT: Fast enough. Only something like less than a minute for this 6GB file.)

Is calculating hash faster than just using "diff"?

QuickHash offers 9 algorithms.
Which is fastest?

Hex Fiend seems to be quick also, but a little clumsier to work: you'll have to open both files separately before you can compare. But it seems to use very little energy (cpu time), maybe it offloads the usage to some other process?

 

[toke lahti]

In appstore, when I search "hash", I get lots of answers. If I search "hash comparison", I'll get nothing.
Most apps maybe just calculate the hash of one file / folder?

Would it be good idea to store the hash result in file's info's Comment area?

There seems to be some apps for even copying files that verify with hash after copying.
Like "TeraCopy".
I guess CCC is not handy for copying just one or few files?
Problem with appStore for me, is the lack of info about options. You should just test every app that you find. Googling gives more info.

Is there any well known, long time, reliable, etc. file copying apps that could handle the verifying "on the fly"?

RapidCopy says that it has both "diff copy" and "checksum verify copy". How do these differ?