Using the cat Command To Hide Files Inside Other Files

cat is a standard command from Unix operating systems, such as BSD and Mac OS X, and Unix-like operating systems, such as Linux, that can be used to concatenate and display files. In this tutorial, I'm going to teach you how to hide any file inside any other file using cat, such that no one will every know the hidden file is there. This obviously has a number of uses, including providing another layer of protection for sensitive information such as bank numbers, personal information, etc.

WARNING: this is an advanced trick that requires the use of the command line. If you are scared of using the command line, don't bother continuing.

Ok, now that that's out of the way, pick a file you want to hide and another file you want to hide it in and place both files on your desktop. In my case, I'm going to hide an archive
inside a picture

Next, open a terminal. For Mac users, go to Applications => Utilities => Terminal.app; for Linux users, you'll have to find out where your particular distro puts it. Switch to your desktop:

cd Desktop

Now, we're going to perform the cat command:

cat archive.rar >> 1.jpg

Now my archive file is concatenated to the end of the picture file. If I double-click on the picture file, it will open in my picture-viewing program without any indication that it is abnormal in any way. However, as you can see from these before/after pics:

the picture's file size is now much larger, thanks to it having the archive attached. Anytime you want to access your hidden file, just rename your file to the hidden file's extension and open as normal:



Note: If you plan on hiding anything really important in a file using this method, I also suggest using some sort of encryption, in case someone actually finds it. This obfuscation just adds another layer of protection for your information.

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How To Backup Your DVDs using DVDShrink

The most common question people ask me is how to backup commercial DVDs (which usually come in DVD-9 format) for burning to regular, run-of-the-mill blank DVDs (DVD-5 format). There are many ways to accomplish this, but one of the easiest is to use DVDShrink. It's a closed-source program that's available for Windows users, although Linux users (such as myself) can run it effectively through WINE.

Step 1

The first step is to download DVDShrink. It's pretty easy to find and you can download it here or here. After that, double-click the installer; the default options should be fine for most users.

Step 2

After you've installed DVDShrink, open the program. You should get a window that looks something like this:



Next, click the "Open Disc" button at the top and select your DVD drive from the menu (usually the D: drive in a standard Windows environment):



DVDShrink will now begin analyzing your DVD. This usually takes around 2 minutes. You can uncheck the box labeled "Enable video preview" if you are worried about spoilers:



Step 3

When it's finished analyzing, you should end up with the DVD structure in the left panel and some compression options in the panel on the right, like this:



Next just click on the "Backup!" button at the top:



You should get a menu like this:



From the "Select backup target" pull-down menu, select "Create ISO image file" and then click the "OK" button:



This will make an exact copy of your DVD, shrunken down to fit a single-layer DVD. There are many other options you can fiddle with in DVDShrink, such as removing sound from menus or reducing the quality of unimportant features to improve the quality of the main movie, but they're not really *necessary* so I'm not going to cover them here.

When DVDShrink finishes encoding, you should have an image file (ends in .iso) that will fit on a standard 4.7GB single-layer DVD. To burn it, you need to use an external program with image-burning capabilities, such as Nero or Alcohol 120%. I personally use the shareware demo version of a program called DVDSanta available free from various places, including here.

If you get this error:

then your DVD uses an unusual copy-protection mechanism that DVDShrink cannot bypass. If this happens, you'll have to rip the DVD using another program first, such as DVD Decrypter, and then use DVDShrink to resize it (Note: this error may also appear when running the program through WINE. Thus, Linux users are encouraged to use DVD Decrypter first).

Copyright notice: using this method to rip commercial DVDs, even if you own them, may be prohibited in your country. It is best to research the laws in your locale before following these steps.

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