Most of the archived files that you can download from binary Usenet newsgroups have the following filenames: name.part01.rar, name.part02.rar, name.part03.rar etc. You can extract those files with WinRAR of the free program 7-Zip. But sometimes you will see files with the following filenames: name.001, name.002, name.003 etc, which I will call 001 files. In this tutorial you will learn how to extract these files. Extracting isn’t the right name though: normally these files are not compressed like RAR files, but just split by a file splitter, without compression. Joining would be a better term for what we are about to do. A small tutorial from other site
In this tutorial we will try to join the test.mp3 file that I made. As you can see in the image below this file is split into eight pieces that we have to join before we can listen to the test.mp3 file.
We can do this with three different programs: WinRAR, 7-Zip and HJSplit. It is up to you to choose which program you would like to use for this task: WinRAR, 7-Zip or HJSplit. Because many people have WinRAR installed on their PC, I will explain that program first. WinRAR isn’t the best fit for this task though, so if you currently do not use WinRAR, just skip the next part and use 7-Zip or HJSplit.
Joining with WinRAR
Open the first file of the archive (name.001) with WinRAR by double clicking on it in the Windows Explorer. Normally a window will appear asking you which program should be used to open the 001 file (this is because Windows might not know which programs are capable of opening 001 files). So select WinRAR in that window. If WinRAR isn’t listed, press the ‘Browse’ button and navigate to the WinRAR folder on your computer (probably C:Program FilesWinRAR) and select WinRAR. Finally press the ‘OK’ button.
Now there are two possibilities:
1) WinRAR is able to open the file successfully. Now you can extract the archive in the same way you would extract normal RAR archives.
2) WinRAR is unable to open the archive and you get the following error message:
In that case WinRAR is unable to join the files, so we have to try the programs 7-Zip or HJSplit. Both programs are free and will be explained below.
Joining with 7-Zip
The free program 7-Zip is better than WinRAR in joining 001 files.
After installing 7-Zip, right click on the first file (name.001) in the Windows Explorer and choose ‘Extract here’ in the 7-Zip submenu of the context menu. 7-Zip will extract the archive and place the extract files into the same directory as where the source files are located. You could also choose ‘Open archive’ to view the archive in 7-Zip or extract the file to another directory by choosing ‘Extract files’. Easy!
Joining with HJSplit
There is a great chance that the person who posted the files used the program HJSplit to split the file to create 001 files. This freeware program is also able to join 001 files.
You do not have to install HJSplit. Just extract the ‘hjsplit.zip’ and double click on HJSplit.exe to start HJSplit. The main window of HJSplit appears. Since we want to join the files, click on ‘Join’:
Click on ‘Input file’ in the new window:
In the new window select the first file of the files that we would like to join, so test.mp3.001 in this case, and click on ‘Open’ after that.
Click on ‘Start’:
Now HJSplit will join the file.
The files have been successfully joined!
source some other site