(May 2, 2019)
AppImage is a system for the simple use of software on Linux computers. It represents a cross-distribution alternative to the centrally managed package manager systems of Linux distributions . The predecessor was the system klik created in 2004 . klik has meanwhile been replaced by the successor project PortableLinuxApps with similar goals.
Since AppImages carry all the program libraries used, they run on all common desktop distributions such as Ubuntu , openSUSE , Fedora , Debian , Arch Linux or Red Hat Linux without any specific adjustments. With AppImage, programs such as LibreOffice , Firefox , Blender , DigiKam , Kdenlive or Gimp can be used in any version, independent of or in parallel with the version that the distribution itself distributes via its repository .
Copying and starting AppImages does not require root rights. It is sufficient to copy the corresponding file into the user directory or to any data carrier, make it executable and then start it. When starting for the first time, many AppImages ask whether they should be included in a menu. Some AppImages search for newer versions when prompted and suggest a corresponding download if necessary.
If you no longer want to use the respective application, you only have to delete the corresponding file. The file extension (often app or AppImage) is unimportant, it can even be omitted.
Only one file, usually with the extension .AppImage (or .app), is required for each application. This represents a compressed file system image, similar to an ISO image . When the embedded application is started, the file is temporarily integrated into the file system ( “mounted” ) and started using a wrapper script. This way, an AppImage user can even use different versions of the same application at the same time on the same system. In addition to the actual program file, the file contains all the necessary libraries and other components on which the main program depends.
The AppImage file can either be downloaded from an appropriate server from the Internet or generated yourself. So-called “recipes” are available on the AppImage homepage for this purpose. These automatically download all the required components from the manufacturer's website and pack them into an image file.
Applications with AppImage run independently of the distribution, but are difficult to integrate into the overall system. Since all dependencies are also embedded, the update systems of the distributions fail here because they cannot update anything within the AppImages. The security of the system therefore depends on a further update instance with every AppImage installed. However, there are tools that make it possible to automatically build updates from the program and the embedded libraries, structures and services and distribute them to users via a delta update mechanism.
The AppImages require longer start times compared to conventionally installed applications via package management. The dependencies brought along are instantiated independently, i.e. they occupy memory, even if the same libraries have already been loaded and instantiated by other programs. The sharing of resources, an essential part of the operating concept, is thus undermined.
An external sandbox program must be used to isolate an AppImage program.
The AppImage predecessor klik was mainly developed by Simon Peter since 2004. At the beginning of 2010 the development fell asleep and the project homepage could no longer be reached. This was put online again for some time to serve as a reference, but is now probably offline for good.
The main developer was meanwhile working on the follow-up project, which was called PortableLinuxApps and which had similar goals. This includes simplicity, binary compatibility, independence from distribution, usability without installation, even from removable media such as USB sticks and without making changes to the installed Linux operating system, and use as a normal user without administrator rights.
Around 2013 the software was renamed again, is now called AppImage and runs under an MIT license. AppImage is the new format for image files and the AppImageKit is used to create them. The development is now documented in a GitHub directory and is currently (2020) active.
Since August 2017 AppImages u. a. made available in a hub set up for this purpose.
- AppImage Hub Current central AppImage directory
- Linux Apps Another directory that also (but not only) contains AppImages
- Apps Apps at Opdesktop are often also called AppImages
- Tony Mobily: "Interview with Simon Peter, creator of klik" in Free Software Magazine , April 7, 2006 (English)
- AppImage.org follow-up project for portable applications
- github.com/AppImage/AppImageKit/wiki/AppImages Older overview of AppImages on github, which is no longer updated
- Simon Peter: AppImageKit Documentation 1.0. (PDF; 38 kB) (No longer available online.) PortableLinuxApps.org, 2010, pp. 2–3 , archived from the original on November 29, 2010 ; accessed on July 29, 2011 (English): " The AppImage format has been created with specific objectives in mind: Be Simple [...] Maintain binary compatibility [...] Be distribution-agnostic [...] Remove the need for installation [...] Allow to put apps anywhere [...] Do not require recompilation [...] Keep base operating system untouched [...] Do not require root [...] "
- AppImageKit. github.com , accessed January 27, 2020 .