checksum tricks and tips
hints, secrets, behaviours, assumptions and more..

Get the most from your hashing!

checksum represents a whole new way of working with hashes. This page aims to help you get the most out of the experience, wherever you're at..

Absolute beginners..

The basics: checksum creates "hash files". A hash file is a simple, plain text file containing one or more file hashes, aka. "checksums". Hashes are small strings which uniquely represent the data that was hashed. e.g..

cf88430390b98416d1fb415baa494dce *08. Allow Your Mind To Wander.mp3

(Mike Mainieri - Journey Thru An Electric Tube [1968] - I have the vinyl)

If you want to know more about the algorithms that checksum uses to hash files (MD5, SHA1 and BLAKE2), see here.

Once these hashes have been created for a particular file or folder (or disk), you have a snapshot that can be used, at any time in the future, to verify that not one bit of data has changed. And I do mean a "bit"; even the slightest change in the data will, thanks to the avalanche effect, produce a wildly different hash, which is what makes these algorithms so good for data verification.

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The basic checksum tasks..

Most people will simply install checksum, and then use the Explorer context (right-click) menu to create and verify checksums, rarely needing any of the "extra" functionality that lurks beneath checksum's simple exterior. After all, checksum is designed to save you time, as well as aid peace of mind. This is how I mostly use it, too..

Create checksums..

Right-click a file, the checksum option produces a hash file (aka. 'checksum file') with the same name as the file you clicked, except with a .hash extension (or .md5/.sha1, if you use those, instead). So a checksum of some-movie.avi would be created, named some-movie.hash (if you don't use the unified .hash extension, your file would instead be named some-movie.md5 or some-movie.sha1, depending on the algorithm used).

Right-click a folder, the Create checksums.. option will produce a hash file in that folder, containing checksums for all the files in the folder (and so on, inside any interior folders), named after the folder(s), again, with a .hash extension, e.g. somefolder.hash

Verify checksums..

Click (left-click) a hash file (or right-click and choose Verify this checksum file..), checksum immediately verifies all the hashes (.hash/.md5/.sha1) contained within.

Right-click a folder, the Verify checksums.. option instructs checksum to scan the directory and immediately verify any hash files contained within.

That's about it, and this simple usage is fine for most situation. But occasionally we need more..

checksum launch modifiers..

When you launch checksum, you can modify its default behaviour in two important ways.

a <SHIFT> Key, checksum's main modifier key

The first modifier is the <SHIFT> key. Hold it down when checksum launches, and you pop-up the one-shot options dialog, which enables you to change lots of other things about what checksum does next. This works with both create and verify tasks, from explorer menus or drag-and-drop. Here's what the one-shot create dialog looks like..

an image of checksum's one-shot hash creation dialog

In there, as you can see, you can set all sorts of things. Hover over any control to get a Help ToolTip (you might need to repeat that to read the entire tip!). You can also drag files and folders directly onto that dialog, if you want to alter the path setting without typing. Same for the verify options.

The file mask: input is, by default, *.*, which means "All files", "*" being a wildcard, which matches any number of any characters. You can have multiple types, too, separated by commas. For example, if you wanted to hash only PNG files, you would use *.png; if you wanted to hash only text files beginning with "2008", you could use 2008*.txt, and so on.

If you click the drop-down button to the right of the input, you can access your pre-defined file groups, ready-for-use (you can easily add to/edit these in your checksum.ini)..

checksum creation options dialog, file types group drop-down, regular Windows masks apply

NOTE: Normally one drops folders into checksum's create options (path input). If you drop a file onto the create options, the path is inserted into the path: input, and the file name is added to the mask input - it is also inserted into the drop-down lost in case you need to get back to it.

If you drop multiple files into the create options, checksum will create a custom file mask from your selection. For example, if you dropped these three files; "hasher.jpg", ".txt" and "security.pdf", checksum would create the mask: "*.jpg,*.txt,*.pdf".

Here is what the one-shot verify options dialog looks like..

an image of checksum's one-shot hash verification dialog

a <Ctrl> Key, checksum's second modifier key

The second modifier is the <Ctrl> key. Hold it down when checksum launches and you force checksum into verify mode, that is to say, no matter what type of file it was, you instruct checksum to treat it as a hash file, and verify it. This works with drag-and-drop too, onto checksum itself, or a shortcut to checksum. checksum's default drag-and-drop action is to create hashes.

Amongst other things, this is useful for verifying folders in portable mode, simply Ctrl+drag-and-drop the folder directly onto checksum (or a shortcut to it), and all its hashes will be immediately verified.

Hit the modifier key as soon as checksum launches, in other words, hit the <SHIFT>/<Ctrl> key right after you choose the Explorer menu item, or before you let go of a drag & drop, and so on. Hold the key down until checksum appears a moment later.

batch processing..

hashDROP icon (nicked from somewhere, I think!hashDROP
A batch-processing front-end for checksum..

Because checksum can be controlled by command-line switches, it's possible to create all sorts of interesting front-ends for it. The first of these to come to my attention, is a neat wee application called "hashDROP", which enables you to run big batches of jobs through checksum, using a single set of customizable command-line switches.

As developer seVen explains on the hashDROP page..

hashDROP is a front-end for checksum which enables you to queue a bunch of jobs (files/folders) and then pass them all through checksum with your own custom switches in one batch process.

On seVen's desktop, at least, it looks something like this..

thumbnail image of hashDROP window, create tab
thumbnail image of hashDROP window, verify tab

hashDROP has already earned a place in my SendTo menu. Good work, seVen! For more information, documentation, and downloads, visit the hashDROP page.

Batch Runner logo/iconBatch Runner
Run multiple programs in a batch..

I originally designed Batch Runner to run a big batch of tests on checksum before release, but it has since proven useful for other tasks, so I spruced it up a bit, made it available.

If you want to run loads of hashing jobs using the same switches, hashDROP is probably more useful to you. But if you want to run lots of checksum jobs with different switches, or as part of a larger batch of jobs involving other programs, then check out Batch Runner.

Batches can be saved, selected from a drop-down, run from the command-line, even from inside other batches, so it's handy for repetitive scheduled tasks, or application test suites, as well as general batch duties. At least on my desktop, it looks like this..

thumbnail image of the Batch Runner window

Automatic Music playlists..

Perhaps checksum's second most common extra usage is making music playlists. After you have ripped an album, you will most likely want a playlist along with your checksums, so why not do both at once? checksum can.

Right-click a folder and SHIFT-Select the checksum option (which pops up the one-shot options dialog), check either the Winamp playlists (.m3u/.m3u8) or shoutcast playlists (.pls) option, and then do it now! You're done.

By default, checksum will also recurse (dig) into other folders inside the root (top) folder. Now you've got music playlists that you can click to play the whole album in your media player.

Note that checksum will thoughtfully switch your file masks to your current music group when you select a playlists option, reckoning that you'll probably only want to actually hash the music files, not associated images, info files and such, but it's easy enough to switch it back to *.* (hash all files) if you need that. The rationale behind this being that it's what most people want, so the majority get the simpler, two-click task.

If you do this sort of thing a lot, check out the next section, for how to put this functionality directly into your Explorer context menu, and skip the dialog altogether..

Custom Explorer Context Menu Commands made easy.. custom Windows explorer context menu command

On the subject of music files, you may encounter a lot of these, and fancy creating a custom explorer right-click command along the lines of "checksum all music files", or something like that. No problem; you can simply create a new command in the registry, add the "m" switch add your file masks, right?

But what if you change your file masks? Perhaps add a new music file type? Do you have to go and change your registry again? NO! checksum has it covered. Instead of specifying individual file masks, use your group name in the command, e.g. m(music) and checksum applies all the file masks from that group automatically, so your concept command is always up-to-date with your latest preferences.

Here's an example registry command that would do exactly that. Copy and paste into an empty plain text file, save as something.reg, and merge it into your registry. If you installed checksum in a different location, edit the path to checksum before you merge it into the registry (not forgetting to escape all path backslashes - in other words, double them)..

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\shell\01b.checksum music]
@="Checksum &MUSIC files.."

[HKEY_CLASSES_ROOT\Directory\shell\01b.checksum music\command]
@="\"C:\\Program Files\\corz\\checksum\\checksum.exe\" crm(music) \"%1\""

NOTE! If you add a "3" to the switches [i.e. make them c3rm(music)] you'll get a media player album playlist files created automatically along with the checksum files. Groovy! Here's one I prepared earlier.

Setting new default Explorer context actions..

You can also change checksum's default Explorer commands, as well as add new commands, without going anywhere near the registry. Simply edit the installer's setup.ini file, [keys] section. For example, to always bring up the one-shot options dialog when creating checksums on folders and drives, you would add an "o" to those two commands..

HKCR\Directory\shell\01.|name|\command="|InstalledApp|" cor "%1"
HKCR\Drive\shell\01.|name|\command="|InstalledApp|" cor "%1"
Then run checksum's installer (setup.exe), and install/reinstall checksum with the new options. From then on, any time you select the "Create checksums.." Explorer context menu item, you will get the one-shot options dialog. If you would prefer to synchronize hashes under all circumstances, add a y, and so on.

Creating checksums "quietly"..

If you want to script or schedule your hashing tasks, you will probably want checksum to run without any dialogs, notifications and so forth. If so, add the Quiet switch.. q

When the q options is used alone, if checksum encounters existing hash files, it continues as if you had clicked "No to All", in the "checksum file exists!" dialog, so no existing files are altered in any way. This is the safest default.

If you would prefer checksum to act as if you had clicked "Yes to all", instead, use q+, and any existing checksums will be overwritten.

If you want synchronization, add a y switch (it can be anywhere in the switches, so long as it's in there somewhere, but qy is just fine)

Quiet operation also works for verification, failures are logged, as usual. Like most of checksum's command-line switches, these behaviours can be set permanently, in your checksum.ini.

Working with Cross-Platform hashes..

checksum has a number of features designed to make your cross-platform, inter-networking life a bit easier.

You don't have to do anything special to verify hash files created on Linux, UNIX, Solaris, Mac, or indeed any other major computing platform; checksum can handle these out-of-the-box.

If you need to create hash files for use on other platform, perhaps with some particular system file verification tool, checksum has a few preferences which might help..

You will perhaps appreciate checksum's plain text ini file (checksum.ini) containing all the permanent preferences. Inside there you can set not only which Line Feeds checksum uses in its files (Windows, UNIX, or Mac), but also enable UTF-8 files, single-file "root" hashing, generic hash file naming, UNIX file paths, and more. Lob checksum.ini into your favourite text editor and have a scroll.

checksum in your SendTo menu..

There are a number of ways to run checksum. One handy way, especially if you are running checksum in portable mode without Explorer menus, is to keep a shortcut to checksum in the SendTo menu.

Simply put; any regular file or folder sent to checksum will be immediately hashed. Send a checksum file (.hash, .md5, .sha1, plus whatever UNIX hash files you have set), and it will be immediately verified. If you want extra options, hold down the <SHIFT> key, as usual.

If you want to send a non-checksum file, but have checksum treat it as a checksum file, hold down the <Ctrl> key during launch, to force checksum into verify mode (either just after you activate the SendTo item, or perhaps easier; hold down <SHIFT> AND <Ctrl> together while you click, to bring up the one-shot verify options). This is also handy for verifying folder hashes.

How to accurately compare two folders or disks.

This is an easy one. First, create a "root" hash in the root of the first (source) folder/disk, then copy the .hash file over to the second (target) folder and click it.

That's it!

For situations where you don't need a permanent record of the hashes, you can fully automate the process of comparing two folders with simple checksum.

How to accurately compare two CDs, DVDs, etc.
(even when they don't have hash files on them)..

When hashing read-only media, obviously we cant store the hash files on the disk itself. However, thanks to checksum's range of intelligent read-only fall-back strategies, you can make light work of comparing read-only disks with super-accurate MD5 or SHA1 hashes, even if those disk were burned without  hashes.

All we need to do, is ask checksum to create a "root" hash file of the original disk, using the "Absolute paths" option. This will produce a hash file containing hashes for the entire disk, with full, absolute paths, e.g..

531a3ce6b631bb0048508d872fb1d72f *D:\Sweet.rar
558e40b6996e8a35db668011394cb390 *D:\Backups\
832e98561d3fe5464b45ce67d4007c11 *D:\Sales Reports\

There are a few ways to achieve this. For one-off jobs, you can simply add k1 to your usual command-line switches. For example, to create a recursive root hash file of a disk, with absolute paths, you would use crk1.

Another way, is to set (and forget) checksum's fallback_level preference to 2, inside checksum.ini..


With fallback_level=2, when checksum is asked to create hashes of a read-only volume, it will fall-back to creating a single "root" hash with absolute paths, inside your fall-back location (also configurable), which is exactly what we need!

Then in the future, to verify the original disk, or copies of the disk; you simply insert it, and click the hash file.

You can store the .hash file anywhere you like; so long as the disk is always at D:\, or whatever drive letter you used to create the .hash file originally, it will continue to function perfectly.

If you want to know more about checksum's read-only fall-back strategies, see here.

Or accurately compare a burned disk to its original .iso hashes..

If you have a .hash file of the original .iso file, in theory, a future rip of the disk to ISO format, should produce an .iso file with the exact same checksum as the original. My burner is getting old, but I needed to know, and so tested the theory.

I Torrented an .iso file of a DVD (Linux Distro) - the hashes were published onsite, checksum verified these were correct. I burned the disk to a blank DVD-R, and then deleted the original .iso file. Everything is now on the disk only. The .hash file is still on my desktop.

Then I used the ever-wonderful ImgBurn, to read the DVD to a temporary .iso file on my desktop.

Fortunately, the .iso file, and the original .iso file had the same name, so I didn't need to edit the .hash file in any way. Then the moment of truth. I click the .hash file, and checksum spins into action, verifying. A few seconds later... Beep-Beep! No Errors! It's a perfect match!

I can't speak for other software, but with ImgBurn at least, a burned disk can produce an .iso file with a hash bit-perfectly identical to that of the original .iso file used to create the disk, and can be relied upon for data verification. Good to know.

checksum as an installer watcher..

Because checksum can so accurately inform you of changes in files, it can function as an excellent ad-hoc installer watcher. All you do is create a root checksum for the area you would like to watch. Run the installer. And afterwards, verify the checksum. If anything has changed, checksum will let you know about it, with the option to log the list to funky XHTML or plain text.

Similarly, checksum can be utilized in any situation where you need to know about changed files. You can even use it to compare registry files, one exported before, the other after an install or other process. If the hashes match, there's no need to look further.

checksum's custom command-line switches..

Click & Go! is the usual way to operate checksum; but checksum also contains a lot of special functionality, accessed by the use of "switches"; meaningful letter combinations which instruct checksum to alter its operation in some way.

If you have some unusual task to accomplish, the one-shot options dialog enables you to manipulate the most common switches with simple checkbox controls. You can see the current switches in a readout, updating dynamically as you check and uncheck each option. But this output is also an input, where you can manipulate the switches directly, if you wish. If that is the case, you will probably find the following reference useful.

You may also find this section useful if you are constructing a full checksum command-line for some reason, maybe a Batch Runner command or batch script, or custom front-end for checksum, or altering your explorer context menu, or creating a scheduled task, or some Übertask for your Run command (Win+R) or something else. In each case, switches are placed before the file/folder path, for example; the full command-line to verify a checksum file might look like this..

C:\Program Files\corz\checksum\checksum.exe v C:\path\to\file.hash

Here are all the currently available switches:

Create checksums.
Verify checksums.
Recurse (only for directories).
Synchronize (add any new file hashes to existing checksum files).
During creation: create individual hash files (one per file).

During verification: performs hash search for individual file (see examples, below).

Create SHA1 checksums (default is to create MD5 checksums).
Create BLAKE2 checksums (default is to create MD5 checksums).
UPPERECASE hashes (default is lowercase).
File masks. Put these in brackets after the m. e.g..  m(*.avi,*.rm)
Note: You can use your file groups here, e.g. m(music)
Custom hash name (think: "John"!). Put this in brackets after the j. e.g..  j(my-hashes)
Output Directory. Put this in brackets after the d. e.g..  d(C:\hashes)
NOTE: Make this the last bracketed switch on your command-line, i.e. m(..)j(..)d(..).
Add file extensions to checksum file name (for individual file hashes)..
Create one-file "root" checksums, like Linux CD's often have.
Create .m3u/.m3u8 playlists for all music files encountered (only for folder hashing)..
Create .pls playlists for all music files encountered (only for folder hashing)..
Quiet operation, no dialogs (for scripting checksum - see help for other options)..
Hide checksum files (equivalent to 'attrib +h').
One-shot Options. Brings up a dialog where you can select extra options for a job.
(to pop up the options at run-time, hold down the <SHIFT> key at launch)
Beeps. Enable audio alerts (PC speaker beeps or WAV files).
ToolTip. Enable the progress ToolTip windoid.
No Pause. Normally checksum pauses on completion so you can see the status. This disables it.
(note: you can also set the length of the pause, in your prefs)
Absolute Paths. Record the absolute path inside the (root) checksum file.
Use this only if you are ABSOLUTELY sure the drive letter isn't going to change in the future..
Log to a file
(if there are failures, checksum always gives you the option to log them to a file)
Go to errors.
If a log was created; e.g. there were errors; open the log folder on task completion.
Log everything.
(the default is to only log failures, if any).
Update changed hashes. (think: reWrite)
(during verification, hashes and timestamps for "CHANGED" files can be updated in your .hash file).
During creation: used to specify ignored directories, using standard file masks.
e.g. checksum.exe cr1x(foo*,*bar,baz*qux) "D:\MyDir"

During verification: delete missing hashes.
(hashes for "MISSING" files are removed from your .hash file).

Only verify these checksum files.
(followed by algorithm letter: am for MD5, as for SHA1, a2 for BLAKE2 - see example below).
Shutdown when done.
Handy for long operations on desktop systems. A dialog will appear for 60 seconds, enabling you to abort the process, if required

The 'a', 'f', 'g', 'l' and 'w' switches only take effect when verifying hashes.

The '1', '2', '3', 'd', 'e', 'h', 'j', 'k', 'm', 'o', 'p', 's', 'u', and 'y' switches only take effect when creating hashes.

The 'i' and 'x' switches have different functions for creation and verification.

In other words..

global switches = b, n, o, q, r, t, z.
creation switches = 1, 2, 3, c, d, e, h, i, j, k, m, p, s, u, x, y.
verify switches = a(m/s/2), f, g, i, l, v, w, x.

Switches can be combined, like this..

… checksum.exe v "C:\my long path\to\files.md5"
[ note 'long' path (with spaces) enclosed in "quotes" ]
… checksum.exe crim(movies) c:\downloads
[ create individual checksums for all my movie files - note use of group name ]
… checksum.exe vas c:\archives
[ check all *.sha1 files in the path, not *.md5 files ]
… checksum.exe c3rm(music) p:\audio
[ recursive music file checksum creation, with automatic playlists ]
… checksum.exe cr1m(*.zip) d:\
[ create a "root" checksum for all zip files on drive D: ]
… checksum.exe vi d:\path\to\some\video file.avi
[ search for matching entry for "d:\path\to\some\video file.avi" and verify that one file ]
… checksum.exe crkq1m(movies)j(video-hashes)d(@desktop) v:\
[ quietly create a "root" checksum (named "video-hashes.hash") for all movie files on drive V: and place it on the desktop ]

note: Although it won't appear in the options dialog, the custom name, "video-hashes", will still be set when you begin the job.


And remember, if there's some specific behaviour that you want set permanently, you can do that, and a lot more, inside checksum.ini..

working with checksum's UNIX-style preference file..

checksum has a lot of available options. Here is a page that will help you get the most out of them.

checksum icon/logo, in super-large 256 pixel size PNG!

I do requests!

If there's something you would like to accomplish with checksum, but don't think think checksum can; feel free to request a feature, below..

Request a feature!

If you think you have found a bug, click here. If you want to suggest a feature, leave a comment below. For anything else, click here.

previous comments (seven pages)   show all comments

Art - 28.09.12 9:26 pm

Hi Cor,
Excellent work on checksum, impressive amount of effort to cater for (so many!) various options. Still having some trouble to make it perform the way I'd like though. I'm wondering whether I've misunderstood the .ini settings, and whether you could explain.

The problem: I need to protect an entire OS inside a virtual machine from user-tampering, more specifically, from introducing their own executables renamed as OS .exes, .dlls, coms, and such. (I can prevent any unrecognised process from executing using other means). So I set out_dir to some location users can neither see nor access, and run checksum.exe cr on c:\windows\system32 with a mask for *.exe,*.dll etc, set absolute_paths=true, and all .hash files are created in my destination dir as expected.
But when I wish to verify, I call checkum v <hash-path>, and I get a log with errors for every single file as "missing" because it apparently still expects each hash file in the associated source dir. (It works fine if hashes are written out there.) Unfortunately, this is not an option for me because even with hidden attribute it would be trivially easy for users to find the hashfiles there, figure out that it's md5 or sha1, and edit it to match the rogue executable that is to replace the original. I could do a checksum on the hashfiles themselves, and so on, but life's too short for infinite recursion. smiley for :)

So my question is, what .ini settings would cause checksum.exe to look for the source files in their original location regardless of where the hashfiles themselves are stored? Despite your extensive documentation in ini and on the web, I haven't figured it out yet. What might I be doing wrong?

Thanks in advance for any help you may be able to provide.

ensure you are using "root" hashing, that's a 1 on the command-line, or..


in the ini file. Currently, checksum only creates absolute paths for root .hash files. For you needs, a single .hash file sounds like a better option, anyway.

;o) Cor

indigital - 03.01.13 11:01 am


First and foremost, thank you for your hash tool.

I'm trying to create a checksum with the parameter "1sq" of the following folder/file:

"z:\Filme_1\Die Geschichte des Jungen, der geküßt werden wollte.The Story of a Boy Who Wanted to Be Kissed.L'histoire du garçon qui voulait qu'on l'embrasse.Französisch\L'Histoire du Garcon qui voulait qu'on l'Embrasse.Fr.avi"

Most likely due to the path and file name length checksum isn't able to store the sha1 file in the folder. To me it appears that the hash creation itself is done.

Do you see any solution to that problem?



Yes, don't break Windows' path character limit. It's just asking for all-round trouble. ;o) Cor

ps. Upgrade to the latest version, LONG PATHs are now supported.

Lucas - 06.01.13 10:46 am

Hi corz

I'm writing here, cause I've send 2 emails to you, but they were left without a response.

Apologies. It's the time of year, the inbox fills quickly and only really high priority stuff gets attention. I get there in the end!

First of all great program, and the registration procedure(purchase procedure) made me smile a bit. You have pretty good sense of humour.

Ok, to the main point of my message. I like the synchronize option, but one thing I'm missing and I think it would benefit the application, is checking for the files that are not there anymore, and while creating checksum with the "synchronize" option, to remove those entries from the hash file created before.

Can you implement this feature in the next version of corz checkusm?

ps. When you will be responding to this message can you let me know that you did on the email, so that I don't have to come here every day and check it manually? smiley for ;)


This has been asked and answered (on the page you originally posted this) more than once. I'll certainly look into it as an option, but there are no immediate plans to rewrite the way checksum works. If it's any consolation, the next version of checksum has the option to ignore missing files. ;o) Cor

colorfred - 27.08.13 11:16 pm

First thing, great work! So far, it looks like it already does just about everything I need. What I really need is the command line version to return a pass/fail that I can easily capture so I can have a script perform certain operations in case of failure. What I am thinking is using this as part of a Jenkins job (a plugin for Jenkins might be a potential add on for you?? hint-hint-nudge-nudge) where if the checksum fails, I send an email to folks about the failure.

checksum already does this! If you need a hand with the command-line, or with capturing the result, let me know.

;o) Cor

Chris - 03.11.13 8:04 am

I can say that I'm very happy with your nice checksum tool. The only missing crucial function is to support the handling of multiple selected files/folders. Very often, I have to place checksums that way, but at different locations. So preparing a separate script is no option at all.

Please add support for selecting multiple files/folders.

Thank you

Already done. Check the version.nfo ("itstory" link at the top of this page). ;o) Cor

Steve - 18.12.13 12:20 pm

Great software.

I was wondering if it's possible to create one hash of an entire directory structure so the .hash file has one hash in it.

I want to be able to compare that 2 directories (Main & backup) are identical.


Yes! To compare directories, simply create a root hash (use the "1" switch on the command-line, or easier; check the root hash option in the one-shot options dialog) in the root of the first directory. Then copy the .hash file over to the second directory and click it. Job Done.

If you do this a lot, consider adding a custom command for it to your Explorer's context (right-click) menu - there's a section on how to do this on this very page!

;o) Cor

Robert F. - 18.02.14 10:18 pm


this seems to be a very great and valuable tool. As I've been looking for it for a time now, I'm really happy and thankful. Tried around and everything works great - good usability and sooo fast under Windows.
And with a little, very easy, customization the hash-files are compatible to md5deep under lx, too.

I will use this tool mainly for ensuring integrity and consistency among my multimedia directory trees (mainly photos), including backup / archive trees and current photo workflow.

There is one remaining question, a cmdline switch combination (or ini setting) I must have missed and I simply cannot find it in the online docu or by playing around.

It's regarding hash verification.
When I verify a larger tree, I can easily find (and get a report about) missing and changed files.
But at the same time I would like to know whether there are any new files in the tree (valid files that match the pattern, are not excluded, but do not have any line in the hash-file).

It would be like ... calling checksum vyr, which does not work together (can be called together, but does not report new files).

To make a clear point (as English is obviously not my native language and what I write could easily be misleading):

I am just looking for a report / log of additional, unhashed files during a verification run.
Did I miss something very simply and obvious? Could you be so kind to help or hint me?

Or is the only solution to run checksum twice, once "vr" (to get missing and changed) and then "y" (to hash new ones). But with this attempt I did not find the possibility to obtain a summary log of the newly added files. Of course it would be preferable to get the new files just reported and have the possility to deceide whether to add them to the hashtable in a 2nd run (or simply to delete them if they are there for no good).

Thank you again and greetings from Austria,
Robert F.

During verification, checksum doesn't look at the file system, it simply reads the .hash file(s) and verifies that the checksums within are valid.

If you want to create/add hashes, you need to run checksum in create mode (with synchrinize enabled/chosen). Any new hashes will simply be tagged on to the end of the .hash file. You can have checksum time-stamp the entries, so it's easy enough to see what was added, see: do_timestamp=false in your checksum.ini (set it to true, obviously!).

;o) Cor

ps. thank you for your support! much appreciated!

supernoob - 21.02.14 6:26 am


Here is my case:
I have a program that can create a bootable disc. I created 6 months ago one and decided to make an iso file from it and save it. Then, today I grab the same program and did again a bootable disc and created a new iso file as well just like the last time. Surprisingly, at least for me, both iso files have exactly the same checksum, I mean same md5 and SHA-1.
I thought every time I create an iso file from a CD the resulting file had a different hash or if I burned different bootable CDs with the same creator program and make iso files from each one, the resulting hash should be different. But no, it's the same.
Is this correct and I am missing something?


If the bootable disk is the same (same creator app, same settings), there's no reason why the checksum wouldn't also be the same.

The real question is, what made you decide to create another bootable disk when you already have one?

;o) Cor

Mike - 19.05.14 2:39 am

Got a problem.

Just finished a full 4TB disk hash to root (1day 5hrs!!) and decided to check it was ok so ran checksum again using 'create' followed by synchronise not expecting to find anything, that would be my check. BUT ... it found a missing movie folder (Zero D*** Thi*ty) and began creating fresh checksums. As nothing had changed and there was literally only 5 mins between runs this must be a bug, yes? Something to do with the folder and files starting with 'Z' maybe?? Both runs of checksum finished with success but the first run did NOT check all of the disks filestore.

In actual fact, there was 1 day 5 hours between runs (building the list of current files is the first thing checksum does). The folder was most likely been added during that time. By the way, that does seem a bit slow. Perhaps that disk needs defragmented. ;o) Cor

jumperalex - 20.08.14 8:48 pm

OK so I erroneously emailed you (vice using this form) about a feature request concerning adding Tiger and Whirlpool hashes to be compatible with hashdeep. Ignore that please.

What will REALLY be clutch, and will help the entire headless media server community like Limetech's Unraid community is if you can release a command line utility for linux. I know you've got a gui version, but it would be best if we could avoid having to do that on generally headless machines. We have the ability (still in beta at the moment) to create Docker Containers and KVM virtual machines that can run Windows or something with KDE, but that is really not an ideal situation for what most of us really need. What we need is a command line that can be scripted and added to cron

100% ideal solution - a slackware 14.1 command line build for native unraid use
90% solution - Arch (for the KVM users) and Ubuntu (for the Dockers users) command line builds

Thank you for your consideration and an awesome tool.


Mike - 20.08.14 9:43 pm

Hi! Is there a way I can check only one file from a folder? I have a .hash file with all the file hashes, but when I tell it to verify it checks all the files which takes too much time.
The only solution I see is to open the hash file in notepad, find the hash of the file I want to check, copy it, then use simple checksum to compare them.

If you want to be able to verify individual files, make individual .hash files (there is an option in the one-shot dialog for this, or use the "i" switch on the command-line). ;o) Cor

ps. I do however like the idea of being able to pluck a single hash, or group of hashes out of a big .hash file, and only verify those. Hmmm.. Let me think about this!

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