If you need to combine text files in cmd.exe, you would issue the following command:
copy file1.txt+file2.txt+file3.txt combined_files.txt
If you wish to do the same for binary files, you would use the following command:
copy /b file1.bin+file2.bin+file3.bin combined_files.bin
To do the same in PowerShell is pretty straightforward. If the destination file does not already exist or already contains content, you’ll want to issue the New-Item command first. If you know it doesn’t exist or is empty, you can skip that line, below.
New-Item -ItemType file ".\combined_files.txt" –force
Get-Content .\file?.txt | Add-Content .\combined_files.txt
Thanks to Gerardo Lopez for his “Combine or Join Two Text Files Using PowerShell” article, which is the basis for this information.