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How to show file extensions for known file types in Windows
When attempting to extract multi-part downloads I've seen a few users being tripped up by the Windows option that hides file extensions for known file types.
Typically they would follow instructions, only to be met with extraction error messages.
What is this option?
For certain file types, Windows can show filenames in two different formats.
For example, if I have a text file called "Futures", the file can be shown in Windows either like so:
or like so:
Why the difference?
It all depends on a certain setting that either shows or hides the file extension, i.e. what comes after the filename in files that Windows recognizes.
Here is an example of a user attempting to extract files with the file extensions hidden. In the first picture you can already tell that file extensions are hidden, as the archive file
CL 10-19.7z is only shown as CL 10-19
This is generally not a problem when having to extract single archive files. When, however, one needs to extract archives that span across multiple files, having the Windows option to keep the file extensions hidden is a problem.
Why is this a problem with multi-part files? FIO's security checks prevent that unknown (and potentially unsafe) file types are uploaded onto the website. Because of these stringent security checks, multi-part downloads need to be renamed prior to upload so that they are recognized by FIO. When downloading them, they need to be renamed again to their original filename.
Windows users that keep the file extension hidden, download the multi-part archive files and rename them will typically see something like this when attempting extraction:
This implies that the user attempted to rename a multi-part archive file adding at the end ".001", ".002" and so on, not realizing that the real file extension is hidden, in which case the operation produces unexpected results.
How can I show extensions for file types when they are hidden then?
Just go to Windows Explorer into Tools -> Folder options (your Windows version may slightly differ), click on the "View" tab, and uncheck this box
For more information about showing/hiding file extensions in Windows check this article out:
Hi,
This post exactly solved my problem of not able to unzip3 parts ES files that you posted in the forum. Thank you so much!
Now I got a new question. All of the downloaded Market Replay data will be saved in my C:/Document/Ninjatrader 8/db/replay folder. If I plan to download 10 years of ES data to do some backtesting, this will quickly fill up my C drive. I currently use a small SSD C drive. Is it okay that I save the data in some other drive and still do the backtesting? Will it affect the testing speed?
As far as I know you can't. NinjaTrader sees the Replay data only in its folder. You can't tell NinjaTrader to go look in a folder other than where it expects to find the files.
What you could do is backtest in segments, i.e. 1-2 years at a time. This would translate into having to move data in and out of the C drive so that it does not fill up too much.
It's a pain, I know, but if you have limited free space I don't see another option.
When I try to extract data files, I'm getting that same error message but the solution isn't working. The only thing I can think of is that windows is renaming the other parts as I download them and maybe that's playing a part. But, I can't download the files in the same directory without changing the name slightly (adding a number). Any solution to this problem?
