The information that specifies which file types are associated with which programs is stored in the Windows registry. These file type associations allow you to double-click on a file to open it in the program in which it was created. Because portable applications you install and run on a USB flash drive do not write settings to the registry, files created using them cannot be automatically associated with the portable applications. You can manually set default programs for specific file types and even remove file type associations for installed programs in Windows 7. However, it is not recommended that you manually change file type associations on a public computer or a friend’s computer.
We found a free, portable tool, called eXpresso, that allows you to temporarily assign a file extension to any program, whether it is an installed program or a portable program running on a flash drive.
Download eXpresso from
You can run eXpresso in 32-bit and 64-bit versions of Windows XP, Windows Vista and Windows 7.
As an example, we will associate .png files with GIMP Portable running on a USB flash drive setup with the PortableApps.com suite. We have previously written about a suite of portable applications you can run on a USB flash drive with a nice menu similar to the Windows Start menu. Both eXpresso and GIMP Portable can be installed on a PortableApps.com USB flash drive.
To install eXpresso, double-click on the .paf.exe file you downloaded.
If the Open File – Security Warning dialog box displays, click Run to continue with the installation.
On the Installer Language dialog box, select the desired language from the drop-down list and click OK.
The setup wizard Welcome screen displays. Click Next.
The Choose Install Location screen displays. If you want to install eXpresso to a different location other than the default location listed in the edit box, use the Browse button to select another location. Because it is a portable program, it does not matter where you install it. The eXpresso installation was set up to work with the PortableApps.com menu system. We installed it to an external drive containing other PortableApps.com programs. Click Install to continue.
The progress of the installation displays. If you want to see the details of the installation process, click Show details.
When the installation is finished, click Finish on the Completing the eXpresso Setup screen.
If you installed eXpresso to a drive containing other portable programs from PortableApps.com and the PortableApps.com menu, double-click the StartPortableApps.exe file on that drive.
The menu should contain an entry for eXpresso. Click on the eXpresso item to run the program.
If you did not install eXpresso to a special PortableApps.com drive, open the program by navigating to the folder where you installed it and double-click on the eXpresso.exe file.
An icon for eXpresso displays in the system tray.
Associate a File Type with a Portable Program
Adding an association to eXpresso for a file type is easy. Simply, double-click on a file of the type you want to associate. For our example, we double-clicked on a .png file.
The following dialog box displays asking if you want to set an association for the selected file type. Click Yes.
The Choose the application that will open XXX files dialog box displays. The XXX is replaced with the file type for the file you opened. Navigate to the folder containing the portable program you want to associate with the selected file type. Select the .exe file for the program and click Open.
NOTE: For programs in the PortableApps.com format, the file type should be associated with the launcher, not the base application. The launcher is the .exe file in the root of the portable program’s folder at the same level as the App folder containing the base application.
A message displays on the icon in the system tray telling you that a new association has successfully been added.
When you double-click on a file of the type you added as an association, the selected program opens…
… and the selected file automatically opens in that program.
This was the first part of a two-part article about using eXpresso to temporarily associate files types with portable programs.
This first part covered installing and running eXpresso and using eXpresso to easily associate a file type with a portable program.
The second part of this article will cover manually adding, editing, and deleting file associations in eXpresso, changing the path to a portable program, and using eXpresso to add portable programs to the Send to menu in Windows. Stay tuned!
by Lori Kaufman