Portable application Facts for Kids

A USB drive can carry portable applications

A portable application (or portable app) is a special type of computer program. It's designed to work without needing to be installed on a computer. This means it doesn't change any files or settings on the computer you use it on. You can easily run it, and then remove it, without leaving anything behind.

Think of it like this: a portable app carries everything it needs with it. It often saves your settings and any files you create right in the same folder where the app itself is. This makes it super easy to move the app, along with your personal settings and data, from one computer to another.

You can store portable apps on many different devices. This includes USB drives, also known as pen drives, or even floppy disks (though those are very old now!). You can also keep them on your computer's main storage, on a shared network drive, or in cloud storage. If an app doesn't need to save any settings, you can even run it from a CD-ROM or DVD-ROM, which are read-only. Some apps come in two versions: one you install, and one that's portable.

Sometimes, regular apps can act like portable ones if you give them special instructions. This might involve typing extra commands when you open the program. For example, you might tell it to use a specific file for its settings.

Just like any other program, portable apps must work with the computer's hardware and its operating system. For some operating systems, like AmigaOS, all apps are naturally portable.

Portable Apps for Windows

Most portable applications for Windows are designed not to leave any files or settings on the computer you're using. They usually don't write information to the Windows registry, which is like a central database for Windows settings. They also try not to store their settings in your user profile folder. Instead, many portable apps keep their settings right in the same folder where the app is located.

Because the location of files can change when you move an app to a different computer (for example, if the drive letter changes), portable apps might use "relative paths." This means they look for files based on where they are, not a fixed location. Many programs aren't built this way. So, a common trick is to use a "launcher program." This launcher copies any needed settings to the computer when the app starts. Then, when you close the app, it moves those settings back to the portable app's folder.

Another way to make Windows apps portable, without changing their original code, is called application virtualization. This is like wrapping the app in a special layer. This layer catches any attempts the app makes to change files or settings on the computer. It then redirects these changes to a different, safe place. The app doesn't even know this is happening, but it makes the app portable.

This same method can be used for smaller parts of an application, like special libraries or components. When these parts are made portable, they can be used with other portable apps. They can also be run multiple times with different settings on the same computer without causing problems. Since these portable parts don't affect the main operating system, they usually don't need special administrator permissions to run.

Portable Apps on Unix-like Systems

Programs made for Unix-like systems (like Linux or macOS) are often designed to be flexible. Unlike many older Windows programs that assumed the user was an administrator, Unix-like systems usually have users with fewer permissions. This means programs must be careful not to try to write to protected areas.

These programs often use a special environment variable called `HOME`. This variable tells the program where your personal home directory is. Programs then store their settings there. For example, the w3m browser might store its settings in a folder like `$HOME/.w3m`. There's also `LD_LIBRARY_PATH`, which helps programs find libraries in non-standard places.

For example, if your portable programs are on a drive mounted at `/mnt`, a command to run a portable app might look like this: `HOME=/mnt/home/user LD_LIBRARY_PATH=/mnt/usr/lib /mnt/usr/bin/w3m www.example.com`

Not all programs follow these rules perfectly. Some might ignore the `HOME` variable and try to find your home directory in a different way. This can make them less portable.

In the 2000s, there were efforts to create special package formats for Linux that didn't need administrator rights to run. Examples include Autopackage and AppImage. These didn't become very popular at first. However, around 2015, the idea of portable, "distro-independent" (meaning they work on different Linux versions) apps gained more interest. Linus Torvalds, who created Linux, even supported AppImage for his Subsurface dive log app.

Many Mac applications are naturally portable. If you can install them by just dragging and dropping them into your Applications folder, they are usually portable. Apps like Mozilla Firefox, Skype, and Google Chrome don't need administrator access. They also don't have to be placed in a central, restricted area. You can even put them in your personal Applications folder (`/Users/username/Applications`), and macOS will recognize them just like apps in the main `/Applications` folder.

Portable application facts for kids

Portable Apps for Windows

Portable Apps on Unix-like Systems

See also