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{{short description|Type of computer program}}
{{Short description|Type of computer program}}
{{Distinguish|software portability|portable executable|multiarchitecture binary}}
{{Distinguish|software portability|portable executable|multiarchitecture binary}}
{{multiple issues|
⚫
{{clarity|date=April 2018}}
{{Original research|article|date=August 2009}}
{{Original research|article|date=August 2009}}
}}
[[Image:USB flash drive.jpg|thumb|right|200px|A [[USB flash drive|USB drive]] can carry portable applications]]
[[Image:USB flash drive.jpg|thumb|right|200px|A [[USB flash drive|USB drive]] can carry portable applications]]
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{{clarity|date=April 2018}}
⚫
A '''portable application''' ('''portable app'''), sometimes also called '''standalone''', is a [[Computer program|program]] designed to read and write its configuration settings into an accessible folder in the computer, usually in the folder where the portable application can be found. This makes it easier to transfer the program with the user's preferences and data between different computers. A program that doesn't have any configuration options can also be a portable application.


A '''portable application''' ('''portable app'''), sometimes also called [[Standalone program|standalone software]], is a [[computer program]] designed to operate without changing other files or requiring other software to be installed. In this way, it can be easily added to, run, and removed from any compatible computer without setup or side-effects.<ref name="PortableApps.com">{{cite web | title = What is a portable app? | publisher = PortableApps.com | access-date=2022-11-15 | url = https://portableapps.com/about/what_is_a_portable_app#definition |at = Definition}}</ref>
⚫
Portable applications can be stored on any [[data storage device]], including internal [[mass storage]], a [[Shared resource|file share]], [[File hosting service|cloud storage]] or external storage such as [[USB flash drive|USB drives]] and [[floppy disk]]s—storing its program files and any configuration information and data on the storage medium alone. If no configuration information is required a portable program can be run from [[file system permissions|read-only]] storage such as [[CD-ROM]]s and [[DVD-ROM]]s. Some applications are available in both [[Installer|installable]] and portable versions.

⚫
In practical terms, a portable application often stores user-created data and configuration settings in the same directory it resides in. This makes it easier to transfer the program with the user's preferences and data between different computers. A program that doesn't have any configuration options can also be a portable application.<ref name="PortableApps.com" />

⚫
Portable applications can be stored on any [[data storage device]], including internal [[mass storage]], a [[Shared resource|file share]], [[File hosting service|cloud storage]] or external storage such as [[USB flash drive|USB drives]], pen drives<ref>{{Cite web |date=2007-01-08 |title=Free Portable Apps and Games for USB ▷ Pendrive Software |url=https://pendriveapps.com/ |access-date=2024-06-17 |website=pendriveapps.com |language=en-us}}</ref> and [[floppy disk]]s—storing its program files and any configuration information and data on the storage medium alone. If no configuration information is required a portable program can be run from [[file system permissions|read-only]] storage such as [[CD-ROM]]s and [[DVD-ROM]]s. Some applications are available in both [[Installer|installable]] and portable versions.


Some applications which are not portable by default do support optional portability through other mechanisms, the most common being [[Command-line interface#Arguments|command-line arguments]]. Examples might include <code>/portable</code> to simply instruct the program to behave as a portable program, or <code>--cfg=/path/inifile</code> to specify the configuration file location.
Some applications which are not portable by default do support optional portability through other mechanisms, the most common being [[Command-line interface#Arguments|command-line arguments]]. Examples might include <code>/portable</code> to simply instruct the program to behave as a portable program, or <code>--cfg=/path/inifile</code> to specify the configuration file location.
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== Portable Windows applications ==
== Portable Windows applications ==


A portable application does not leave its files or settings on the host computer or modify the existing system and its configuration. The application does not write to the [[Windows registry]] nor stores its configuration files (such as an [[INI file]]) in the user's [[home directory|profile]]; instead, it stores its configuration files in the portable directory. Another requirement, since [[Path (computing)|file paths]] will often differ on changing computers due to variation in [[drive letter assignment]]s, is the need for applications to store them in a [[Relative path|''relative'']] format. While some applications have options to support this behavior, many programs are not designed to do this. A common technique for such programs is the [[Comparison of desktop application launchers|use of a launcher program]] to copy necessary settings and files to the host computer when the application starts and move them back to the application's directory when it closes.
Most portable applications do not leave files or settings on the host computer or modify the existing system and its configuration. The application may not write to the [[Windows registry]]<ref>{{cite web | title = "What is a Portable App?" | publisher = PortableApps.com | access-date=2022-11-15 | url = https://portableapps.com/about/what_is_a_portable_app#guidelines |at = Guidelines}}</ref> or store its configuration files (such as an [[INI file]]) in the user's [[home directory|profile]], but today, many portables do; many, however, still store their configuration files in the portable directory. Another possibility, since [[Path (computing)|file paths]] will often differ on changing computers due to variation in [[drive letter assignment]]s, is that portable applications may store them in a [[Relative path|''relative'']] format. While some applications have options to support this behavior, many programs are not designed to do this. A common technique for such programs is the [[Comparison of desktop application launchers|use of a launcher program]] to copy necessary settings and files to the host computer when the application starts and move them back to the application's directory when it closes.


An alternative strategy for achieving application portability within Windows, without requiring application source code changes, is [[application virtualization]]: An application is "sequenced" or "packaged" against a runtime layer that transparently intercepts its file system and registry calls, then redirects these to other persistent storage without the application's knowledge. This approach leaves the application itself unchanged, yet portable.
An alternative strategy for achieving application portability within Windows, without requiring application source code changes, is [[application virtualization]]: An application is "sequenced" or "packaged" against a runtime layer that transparently intercepts its file system and registry calls, then redirects these to other persistent storage without the application's knowledge. This approach leaves the application itself unchanged, yet portable.


The same approach is used for individual application components: [[Run-time library|run-time libraries]], [[Component Object Model|COM]] components or [[ActiveX]], not only for the entire application.<ref>{{cite web|title=Portable Application Conversion Technology|url=http://sphinx-soft.com/Portable/|publisher=Sphinx Software|accessdate=January 19, 2012|archiveurl=https://web.archive.org/web/20100907213345/http://sphinx-soft.com/Portable/|archivedate=September 7, 2010}}</ref> As a result, when individual components are ported in such manner they are able to be: integrated into original portable applications, repeatedly instantiated (virtually installed) with different configurations/settings on the same [[operating system]] (OS) without mutual conflicts. As the ported components do not affect the OS-protected related entities (registry and files), the components will not require administrative privileges for installation and management.
The same approach is used for individual application components: [[Run-time library|run-time libraries]], [[Component Object Model|COM]] components or [[ActiveX]], not only for the entire application.<ref>{{cite web|title=Portable Application Conversion Technology|url=http://sphinx-soft.com/Portable/|publisher=Sphinx Software|access-date=January 19, 2012|archive-url=https://web.archive.org/web/20100907213345/http://sphinx-soft.com/Portable/|archive-date=September 7, 2010}}</ref> As a result, when individual components are ported in such manner they are able to be: integrated into original portable applications, repeatedly instantiated (virtually installed) with different configurations/settings on the same [[operating system]] (OS) without mutual conflicts. As the ported components do not affect the OS-protected related entities (registry and files), the components will not require administrative privileges for installation and management.


Microsoft saw the need for an application-specific registry for its Windows operating system as far back as 2005.<ref>{{cite web|title=Portable Application Registry|url=http://ip.com/patapp/US20070136241|publisher=ip.com|accessdate=January 19, 2012}}</ref> It eventually incorporated some of this technology, using the techniques mentioned above, via its Application Compatibility Database<ref>{{cite web|last=Ionescu|first=Alex|title=Secrets of the Application Compatilibity Database (SDB) – Part 1|url=http://www.alex-ionescu.com/?p=39|accessdate=January 19, 2012}}</ref> using its Detours<ref>{{cite web|title=Detours|url=http://research.microsoft.com/en-us/projects/detours/|publisher=Microsoft Research|accessdate=January 19, 2012}}</ref> code library, into Windows XP. It did not make any of this technology available via its system [[API]]s.
Microsoft saw the need for an application-specific registry for its Windows operating system as far back as 2005.<ref>{{cite web|title=Portable Application Registry|url=http://ip.com/patapp/US20070136241|publisher=ip.com|access-date=January 19, 2012}}</ref> It eventually incorporated some of this technology, using the techniques mentioned above, via its Application Compatibility Database<ref>{{cite web|last=Ionescu|first=Alex|title=Secrets of the Application Compatilibity Database (SDB) – Part 1|url=http://www.alex-ionescu.com/?p=39|access-date=January 19, 2012}}</ref> using its Detours<ref>{{cite web|title=Detours|url=http://research.microsoft.com/en-us/projects/detours/|publisher=Microsoft Research|access-date=January 19, 2012}}</ref> code library, into Windows XP. It did not make any of this technology available via its system [[API]]s.


== Portability on Linux and Unix-like systems ==
== Portability on Unix-like systems ==
{{See also|Autopackage|Zero Install}}
{{See also|Autopackage|Zero Install}}
Programs written with a Unix-like base in mind often do not make any assumptions. Whereas many Windows programs assume the user is an [[Superuser|administrator]]—something very prevalent in the days of [[Windows 95]]/[[Windows 98|98]]/[[Windows ME|ME]] (and to some degree in [[Windows XP]]/[[Windows 2000|2000]], though not in [[Windows Vista]] or [[Windows 7]])—such would quickly result in "Permission denied" errors in Unix-like environments since users will be in an unprivileged state much more often. Programs are therefore generally designed to use the <code>[[$HOME|HOME]]</code> [[environment variable]] to store settings (e.g. <code>''$HOME''/.w3m</code> for the [[w3m]] browser). The dynamic linker provides an environment variable <code>[[$LD_LIBRARY_PATH|LD_LIBRARY_PATH]]</code> that programs can use to load libraries from non-standard directories. Assuming <code>/mnt</code> contains the portable programs and configuration, a command line may look like:
Programs written with a Unix-like base in mind often do not make any assumptions. Whereas many Windows programs assume the user is an [[Superuser|administrator]]—something very prevalent in the days of [[Windows 95]]/[[Windows 98|98]]/[[Windows ME|ME]] (and to some degree in [[Windows XP]]/[[Windows 2000|2000]], though not in [[Windows Vista]] or [[Windows 7]])—such would quickly result in "Permission denied" errors in Unix-like environments since users will be in an unprivileged state much more often. Programs are therefore generally designed to use the <code>[[$HOME|HOME]]</code> [[environment variable]] to store settings (e.g. <code>''$HOME''/.w3m</code> for the [[w3m]] browser). The dynamic linker provides an environment variable <code>[[$LD_LIBRARY_PATH|LD_LIBRARY_PATH]]</code> that programs can use to load libraries from non-standard directories. Assuming <code>/mnt</code> contains the portable programs and configuration, a command line may look like:
Line 30: Line 35:
<code>HOME=/mnt/home/user LD_LIBRARY_PATH=/mnt/usr/lib /mnt/usr/bin/w3m www.example.com</code>
<code>HOME=/mnt/home/user LD_LIBRARY_PATH=/mnt/usr/lib /mnt/usr/bin/w3m www.example.com</code>


A Linux application without need for a user-interaction (e.g. adapting a script or environment variable) on varying directory paths can be achieved with the [[GNU Compiler Collection|GCC]] [[GNU linker|Linker]] option <code>$ORIGIN</code> which allows a relative library search path.<ref name="lgpl">{{cite web|url=http://blog.linuxgamepublishing.com/2009/02/08/our-new-way-to-meet-the-lgpl/|archiveurl=https://web.archive.org/web/20090220234542/http://blog.linuxgamepublishing.com/2009/02/08/our-new-way-to-meet-the-lgpl/|archivedate=2009-02-20 |title= Our new way to meet the LGPL |date=2009-02-08|accessdate= 2011-03-09 |first=Eskild |last= Hustvedt |quote= You can use a special keyword $ORIGIN to say ‘relative to the actual location of the executable’. Suddenly we found we could use -rpath $ORIGIN/lib and it worked. The game was loading the correct libraries, and so was stable and portable, but was also now completely in the spirit of the LGPL as well as the letter!}}</ref>
A Linux application without need for a user-interaction (e.g. adapting a script or environment variable) on varying directory paths can be achieved with the [[GNU Compiler Collection|GCC]] [[GNU linker|Linker]] option <code>$ORIGIN</code> which allows a relative library search path.<ref name="lgpl">{{cite web|url=http://blog.linuxgamepublishing.com/2009/02/08/our-new-way-to-meet-the-lgpl/|archive-url=https://web.archive.org/web/20090220234542/http://blog.linuxgamepublishing.com/2009/02/08/our-new-way-to-meet-the-lgpl/|archive-date=2009-02-20 |title= Our new way to meet the LGPL |date=2009-02-08|access-date= 2011-03-09 |first=Eskild |last= Hustvedt |quote= You can use a special keyword $ORIGIN to say 'relative to the actual location of the executable'. Suddenly we found we could use -rpath $ORIGIN/lib and it worked. The game was loading the correct libraries, and so was stable and portable, but was also now completely in the spirit of the LGPL as well as the letter!}}</ref>


Not all programs honor this—some completely ignore $HOME and instead do a user look-up in <code>/etc/passwd</code> to find the home directory, therefore thwarting portability.
Not all programs honor this—some completely ignore $HOME and instead do a user look-up in <code>/etc/passwd</code> to find the home directory, therefore thwarting portability.


There are also cross-distro package formats that do not require admin rights to run, like [[Autopackage]], [[Klik (packaging method)|klik]] (now called AppImage), or CDE, but which gained only limited acceptance and support in the Linux community in the 2000s.<ref name=glg>{{cite web|url=http://www.gaslampgames.com/blog/2010/11/13/dear-linux-community-we-need-to-talk/|publisher=Gaslamp Games|title=Dear Linux Community: We Need To Talk. |date=2010-10-13 |first=Nicholas |last=Vining |accessdate=2011-01-30 |quote=''The Linux community, in their infinite wisdom, proceeds to flame the hell out of CDE. [...] “We should all just be using package management.” Here is what I want to say, and let my words be carried down from the mountaintops, written on tiny stone tablets: Package management is not a universal panacea.''}}</ref><ref name=byfield>{{cite web|archiveurl=https://web.archive.org/web/20080331092730/http://www.linux.com/articles/60124 |url=http://www.linux.com/articles/60124|title=Autopackage struggling to gain acceptance |first=Bruce |last=Byfield |date=2007-02-12 |accessdate=2012-01-21 |publisher=linux.com |archivedate=2008-03-31 |quote=''If Hearn is correct, the real lesson of Autopackage is not how to improve software installation, but the difficulty -- perhaps the impossibility -- of large-scale changes in Linux architecture this late in its history. It's a sobering, disappointing conclusion to a project that once seemed so promising.''}}</ref><ref>{{cite web|title=AppImages|url=http://elementary-project.com/wiki/index.php?title=AppImages|publisher=Elementary Project |accessdate=January 19, 2012|archiveurl=https://web.archive.org/web/20101213215610/http://elementary-project.com/wiki/index.php?title=AppImages|archivedate=December 13, 2010}}</ref> Around 2015 the idea of portable and distro independent packing for the Linux ecosystem got more traction when [[Linus Torvalds]] discussed this topic on the [[DebConf]] 2014 and endorsed later [[AppImage]] for his [[dive log]] application [[Subsurface (software)|Subsurface]].<ref name="torvalds2014">{{cite web|url=http://meetings-archive.debian.net/pub/debian-meetings/2014/debconf14/webm/QA_with_Linus_Torvalds.webm |title=Q&A with Linus Torvalds |authors=[[Linus Torvalds]] |date=2014-08-29 |publisher=[[debian]].net |work=[[DebConf]] 2014 Portland |accessdate=2016-05-14 |format=video |at=6:28 |quote=I have seen this first hand with the other project I'm involved with, which is my dive log app. We make binaries for Windows and OSX, we basically don't make binaries for Linux. Why? Because making binaries for Linux desktop applications is a major fucking pain in the ass.}}</ref><ref>{{cite web|url=https://plus.google.com/+LinusTorvalds/posts/WyrATKUnmrS|title=This is just very cool.|last=Torvalds|first=Linus|author-link=Linus Torvalds|publisher=[[Google+]]|quote=I finally got around to play with the "AppImage" version of +Subsurface, and it really does seem to "just work".}}</ref><ref>{{cite web|url=https://plus.google.com/+LinusTorvalds/posts/WyrATKUnmrS|title=This is just very cool. |last=Hohndel |first=Dirk|publisher=[[Google+]]|quote=I, as the app maintainer, don't want my app bundled in a distribution anymore. Way to much pain for absolutely zero gain. Whenever I get a bug report my first question is "oh, which version of which distribution? which version of which library? What set of insane patches were applied to those libraries?". No, Windows and Mac get this right. I control the libraries my app runs against. [...] With an AppImage I can give them just that. Something that runs on their computer.|date=2015-11-25}}</ref> For instance, [[MuseScore]] and [[Krita]] followed in 2016 and started to use AppImage builds for software deployment.<ref>{{cite web|last1=Weiss|first1=Isaac |title=MuseScore 2.0.3 is released|url=https://musescore.org/en/node/104676|website=MuseScore.org |publisher=MuseScore |accessdate=2016-04-05}}</ref><ref>{{cite web|title=Krita 3.0 Released|url=https://krita.org/item/krita-3-0-released/ |website=Krita.org |publisher=Krita |date=2016-05-31}}</ref> RedHat released in 2016 the [[Flatpak]] system, which is a successor of Alexander Larsson's ''glick'' project which was inspired by klik (now AppImage).<ref>[https://blogs.gnome.org/alexl/2007/08/07/experiments-with-runtime-less-app-bundles/ Experiments with run-timeless app bundles] by Alex Larsson (2007)</ref> Similarly, [[Canonical (company)|Canonical]] released in 2016 [[Snappy (package manager)|Snap packages]] for [[Ubuntu (operating system)|Ubuntu]] and many other Linux distros.
There are also cross-distro package formats that do not require admin rights to run, like [[Autopackage]], [[AppImage]], or CDE, but which gained only limited acceptance and support in the Linux community in the 2000s.<ref name=glg>{{cite web|url=http://www.gaslampgames.com/blog/2010/11/13/dear-linux-community-we-need-to-talk/|publisher=Gaslamp Games|title=Dear Linux Community: We Need To Talk. |date=2010-10-13 |first=Nicholas |last=Vining |access-date=2011-01-30 |quote=''The Linux community, in their infinite wisdom, proceeds to flame the hell out of CDE. [...] "We should all just be using package management." Here is what I want to say, and let my words be carried down from the mountaintops, written on tiny stone tablets: Package management is not a universal panacea.''}}</ref><ref name=byfield>{{cite web|archive-url=https://web.archive.org/web/20080331092730/http://www.linux.com/articles/60124 |url=http://www.linux.com/articles/60124|title=Autopackage struggling to gain acceptance |first=Bruce |last=Byfield |date=2007-02-12 |access-date=2012-01-21 |publisher=linux.com |archive-date=2008-03-31 |quote=''If Hearn is correct, the real lesson of Autopackage is not how to improve software installation, but the difficulty -- perhaps the impossibility -- of large-scale changes in Linux architecture this late in its history. It's a sobering, disappointing conclusion to a project that once seemed so promising.''}}</ref><ref>{{cite web|title=AppImages|url=http://elementary-project.com/wiki/index.php?title=AppImages|publisher=Elementary Project |access-date=January 19, 2012|archive-url=https://web.archive.org/web/20101213215610/http://elementary-project.com/wiki/index.php?title=AppImages|archive-date=December 13, 2010}}</ref> Around 2015 the idea of portable and distro independent packing for the Linux ecosystem got more traction when [[Linus Torvalds]] discussed this topic on the [[DebConf]] 2014 and endorsed later [[AppImage]] for his [[dive log]] application [[Subsurface (software)|Subsurface]].<ref name="torvalds2014">{{cite web|url=http://meetings-archive.debian.net/pub/debian-meetings/2014/debconf14/webm/QA_with_Linus_Torvalds.webm |title=Q&A with Linus Torvalds |author=Linus Torvalds |author-link=Linus Torvalds |date=2014-08-29 |publisher=[[debian]].net |work=[[DebConf]] 2014 Portland |access-date=2016-05-14 |format=video |at=6:28 |quote=I have seen this first hand with the other project I'm involved with, which is my dive log app. We make binaries for Windows and OSX, we basically don't make binaries for Linux. Why? Because making binaries for Linux desktop applications is a major fucking pain in the ass.}}</ref><ref>{{cite web|url=https://plus.google.com/+LinusTorvalds/posts/WyrATKUnmrS|title=This is just very cool.|last=Torvalds|first=Linus|author-link=Linus Torvalds|publisher=[[Google+]]|quote=I finally got around to play with the "AppImage" version of +Subsurface, and it really does seem to "just work".}}</ref><ref>{{cite web|url=https://plus.google.com/+LinusTorvalds/posts/WyrATKUnmrS|title=This is just very cool. |last=Hohndel |first=Dirk|publisher=[[Google+]]|quote=I, as the app maintainer, don't want my app bundled in a distribution anymore. Way to much pain for absolutely zero gain. Whenever I get a bug report my first question is "oh, which version of which distribution? which version of which library? What set of insane patches were applied to those libraries?". No, Windows and Mac get this right. I control the libraries my app runs against. [...] With an AppImage I can give them just that. Something that runs on their computer.|date=2015-11-25}}</ref> For instance, [[MuseScore]] and [[Krita]] followed in 2016 and started to use AppImage builds for software deployment.<ref>{{cite web|last1=Weiss|first1=Isaac|title=MuseScore 2.0.3 is released|url=https://musescore.org/en/node/104676|website=MuseScore.org|publisher=MuseScore|access-date=2016-04-05|archive-url=https://web.archive.org/web/20160423053503/https://musescore.org/en/node/104676|archive-date=2016-04-23}}</ref><ref>{{cite web|title=Krita 3.0 Released|url=https://krita.org/item/krita-3-0-released/ |website=Krita.org |publisher=Krita |date=2016-05-31}}</ref> RedHat released in 2016 the [[Flatpak]] system, which is a successor of Alexander Larsson's ''glick'' project which was inspired by klik (now called AppImage).<ref>[https://blogs.gnome.org/alexl/2007/08/07/experiments-with-runtime-less-app-bundles/ Experiments with run-timeless app bundles] by Alex Larsson (2007)</ref> Similarly, [[Canonical (company)|Canonical]] released in 2016 [[Snappy (package manager)|Snap packages]] for [[Ubuntu (operating system)|Ubuntu]] and many other Linux distros.


Many Mac applications that can be installed by drag-and-drop are inherently portable as Mac application bundles.<ref>{{cite web | title = Distributing Your Application | publisher = developer.apple.com | accessdate=2017-05-23 | url = https://developer.apple.com/library/content/documentation/Porting/Conceptual/PortingUnix/distributing/distibuting.html}}</ref> Examples include [[Mozilla Firefox]], [[Skype]] and [[Google Chrome]] which do not require admin access and do not need to be placed into a central, restricted area. Applications placed into <code>/Users/username/Applications</code> (<code>~/Applications</code>) are registered with macOS LaunchServices in the same way as applications placed into the main <code>/Applications</code> folder. For example, right-clicking a file in Finder and then selecting "Open With..." will show applications available from both /Applications and ~/Applications. Developers can create Mac product installers which allow the user to perform a home directory install, labelled "Install for me only" in the Installer user interface.<ref>{{cite web | title = Distribution XML Reference | publisher = developer.apple.com | accessdate=2017-05-23 | url = https://developer.apple.com/library/content/documentation/DeveloperTools/Reference/DistributionDefinitionRef/Chapters/Distribution_XML_Ref.html#//apple_ref/doc/uid/TP40005370-CH100-SW35}}</ref> Such an installation is performed as the user.
Many Mac applications that can be installed by drag-and-drop are inherently portable as Mac application bundles.<ref>{{cite web | title = Distributing Your Application | publisher = developer.apple.com | access-date=2017-05-23 | url = https://developer.apple.com/library/content/documentation/Porting/Conceptual/PortingUnix/distributing/distibuting.html}}</ref> Examples include [[Mozilla Firefox]], [[Skype]] and [[Google Chrome]] which do not require admin access and do not need to be placed into a central, restricted area. Applications placed into <code>/Users/username/Applications</code> (<code>~/Applications</code>) are registered with macOS LaunchServices in the same way as applications placed into the main <code>/Applications</code> folder. For example, right-clicking a file in Finder and then selecting "Open With..." will show applications available from both /Applications and ~/Applications. Developers can create Mac product installers which allow the user to perform a home directory install, labelled "Install for me only" in the Installer user interface.<ref>{{cite web | title = Distribution XML Reference | publisher = developer.apple.com | access-date=2017-05-23 | url = https://developer.apple.com/library/content/documentation/DeveloperTools/Reference/DistributionDefinitionRef/Chapters/Distribution_XML_Ref.html#//apple_ref/doc/uid/TP40005370-CH100-SW35}}</ref> Such an installation is performed as the user.


==See also==
==See also==
Line 53: Line 58:
** [[Portable-VirtualBox]]
** [[Portable-VirtualBox]]
** [[Windows To Go]]
** [[Windows To Go]]
* [[Data portability]]
* [[Interoperability]]


==References==
==References==
{{Reflist|30em}}
{{Reflist}}


[[Category:Portable software| ]]
[[Category:Portable software| ]]

Latest revision as of 03:19, 19 August 2024

Not to be confused with software portability, portable executable, or multiarchitecture binary.
A USB drive can carry portable applications

A portable application (portable app), sometimes also called standalone software, is a computer program designed to operate without changing other files or requiring other software to be installed. In this way, it can be easily added to, run, and removed from any compatible computer without setup or side-effects.[1]

In practical terms, a portable application often stores user-created data and configuration settings in the same directory it resides in. This makes it easier to transfer the program with the user's preferences and data between different computers. A program that doesn't have any configuration options can also be a portable application.[1]

Portable applications can be stored on any data storage device, including internal mass storage, a file share, cloud storage or external storage such as USB drives, pen drives[2] and floppy disks—storing its program files and any configuration information and data on the storage medium alone. If no configuration information is required a portable program can be run from read-only storage such as CD-ROMs and DVD-ROMs. Some applications are available in both installable and portable versions.

Some applications which are not portable by default do support optional portability through other mechanisms, the most common being command-line arguments. Examples might include /portable to simply instruct the program to behave as a portable program, or --cfg=/path/inifile to specify the configuration file location.

Like any application, portable applications must be compatible with the computer system hardware and operating system.

Depending on the operating system, portability is more or less complex to implement; to operating systems such as AmigaOS, all applications are by definition portable.

Portable Windows applications

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Most portable applications do not leave files or settings on the host computer or modify the existing system and its configuration. The application may not write to the Windows registry[3] or store its configuration files (such as an INI file) in the user's profile, but today, many portables do; many, however, still store their configuration files in the portable directory. Another possibility, since file paths will often differ on changing computers due to variation in drive letter assignments, is that portable applications may store them in a relative format. While some applications have options to support this behavior, many programs are not designed to do this. A common technique for such programs is the use of a launcher program to copy necessary settings and files to the host computer when the application starts and move them back to the application's directory when it closes.

An alternative strategy for achieving application portability within Windows, without requiring application source code changes, is application virtualization: An application is "sequenced" or "packaged" against a runtime layer that transparently intercepts its file system and registry calls, then redirects these to other persistent storage without the application's knowledge. This approach leaves the application itself unchanged, yet portable.

The same approach is used for individual application components: run-time libraries, COM components or ActiveX, not only for the entire application.[4] As a result, when individual components are ported in such manner they are able to be: integrated into original portable applications, repeatedly instantiated (virtually installed) with different configurations/settings on the same operating system (OS) without mutual conflicts. As the ported components do not affect the OS-protected related entities (registry and files), the components will not require administrative privileges for installation and management.

Microsoft saw the need for an application-specific registry for its Windows operating system as far back as 2005.[5] It eventually incorporated some of this technology, using the techniques mentioned above, via its Application Compatibility Database[6] using its Detours[7] code library, into Windows XP. It did not make any of this technology available via its system APIs.

Portability on Unix-like systems

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See also: Autopackage and Zero Install

Programs written with a Unix-like base in mind often do not make any assumptions. Whereas many Windows programs assume the user is an administrator—something very prevalent in the days of Windows 95/98/ME (and to some degree in Windows XP/2000, though not in Windows Vista or Windows 7)—such would quickly result in "Permission denied" errors in Unix-like environments since users will be in an unprivileged state much more often. Programs are therefore generally designed to use the HOME environment variable to store settings (e.g. $HOME/.w3m for the w3m browser). The dynamic linker provides an environment variable LD_LIBRARY_PATH that programs can use to load libraries from non-standard directories. Assuming /mnt contains the portable programs and configuration, a command line may look like:

HOME=/mnt/home/user LD_LIBRARY_PATH=/mnt/usr/lib /mnt/usr/bin/w3m www.example.com

A Linux application without need for a user-interaction (e.g. adapting a script or environment variable) on varying directory paths can be achieved with the GCC Linker option $ORIGIN which allows a relative library search path.[8]

Not all programs honor this—some completely ignore $HOME and instead do a user look-up in /etc/passwd to find the home directory, therefore thwarting portability.

There are also cross-distro package formats that do not require admin rights to run, like Autopackage, AppImage, or CDE, but which gained only limited acceptance and support in the Linux community in the 2000s.[9][10][11] Around 2015 the idea of portable and distro independent packing for the Linux ecosystem got more traction when Linus Torvalds discussed this topic on the DebConf 2014 and endorsed later AppImage for his dive log application Subsurface.[12][13][14] For instance, MuseScore and Krita followed in 2016 and started to use AppImage builds for software deployment.[15][16] RedHat released in 2016 the Flatpak system, which is a successor of Alexander Larsson's glick project which was inspired by klik (now called AppImage).[17] Similarly, Canonical released in 2016 Snap packages for Ubuntu and many other Linux distros.

Many Mac applications that can be installed by drag-and-drop are inherently portable as Mac application bundles.[18] Examples include Mozilla Firefox, Skype and Google Chrome which do not require admin access and do not need to be placed into a central, restricted area. Applications placed into /Users/username/Applications (~/Applications) are registered with macOS LaunchServices in the same way as applications placed into the main /Applications folder. For example, right-clicking a file in Finder and then selecting "Open With..." will show applications available from both /Applications and ~/Applications. Developers can create Mac product installers which allow the user to perform a home directory install, labelled "Install for me only" in the Installer user interface.[19] Such an installation is performed as the user.

See also

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References

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  1. ^ a b "What is a portable app?". PortableApps.com. Definition. Retrieved 2022-11-15.
  2. ^ "Free Portable Apps and Games for USB ▷ Pendrive Software". pendriveapps.com. 2007-01-08. Retrieved 2024-06-17.
  3. ^ ""What is a Portable App?"". PortableApps.com. Guidelines. Retrieved 2022-11-15.
  4. ^ "Portable Application Conversion Technology". Sphinx Software. Archived from the original on September 7, 2010. Retrieved January 19, 2012.
  5. ^ "Portable Application Registry". ip.com. Retrieved January 19, 2012.
  6. ^ Ionescu, Alex. "Secrets of the Application Compatilibity Database (SDB) – Part 1". Retrieved January 19, 2012.
  7. ^ "Detours". Microsoft Research. Retrieved January 19, 2012.
  8. ^ Hustvedt, Eskild (2009-02-08). "Our new way to meet the LGPL". Archived from the original on 2009-02-20. Retrieved 2011-03-09. You can use a special keyword $ORIGIN to say 'relative to the actual location of the executable'. Suddenly we found we could use -rpath $ORIGIN/lib and it worked. The game was loading the correct libraries, and so was stable and portable, but was also now completely in the spirit of the LGPL as well as the letter!
  9. ^ Vining, Nicholas (2010-10-13). "Dear Linux Community: We Need To Talk". Gaslamp Games. Retrieved 2011-01-30. The Linux community, in their infinite wisdom, proceeds to flame the hell out of CDE. [...] "We should all just be using package management." Here is what I want to say, and let my words be carried down from the mountaintops, written on tiny stone tablets: Package management is not a universal panacea.
  10. ^ Byfield, Bruce (2007-02-12). "Autopackage struggling to gain acceptance". linux.com. Archived from the original on 2008-03-31. Retrieved 2012-01-21. If Hearn is correct, the real lesson of Autopackage is not how to improve software installation, but the difficulty -- perhaps the impossibility -- of large-scale changes in Linux architecture this late in its history. It's a sobering, disappointing conclusion to a project that once seemed so promising.
  11. ^ "AppImages". Elementary Project. Archived from the original on December 13, 2010. Retrieved January 19, 2012.
  12. ^ Linus Torvalds (2014-08-29). "Q&A with Linus Torvalds" (video). DebConf 2014 Portland. debian.net. 6:28. Retrieved 2016-05-14. I have seen this first hand with the other project I'm involved with, which is my dive log app. We make binaries for Windows and OSX, we basically don't make binaries for Linux. Why? Because making binaries for Linux desktop applications is a major fucking pain in the ass.
  13. ^ Torvalds, Linus. "This is just very cool". Google+. I finally got around to play with the "AppImage" version of +Subsurface, and it really does seem to "just work".
  14. ^ Hohndel, Dirk (2015-11-25). "This is just very cool". Google+. I, as the app maintainer, don't want my app bundled in a distribution anymore. Way to much pain for absolutely zero gain. Whenever I get a bug report my first question is "oh, which version of which distribution? which version of which library? What set of insane patches were applied to those libraries?". No, Windows and Mac get this right. I control the libraries my app runs against. [...] With an AppImage I can give them just that. Something that runs on their computer.
  15. ^ Weiss, Isaac. "MuseScore 2.0.3 is released". MuseScore.org. MuseScore. Archived from the original on 2016-04-23. Retrieved 2016-04-05.
  16. ^ "Krita 3.0 Released". Krita.org. Krita. 2016-05-31.
  17. ^ Experiments with run-timeless app bundles by Alex Larsson (2007)
  18. ^ "Distributing Your Application". developer.apple.com. Retrieved 2017-05-23.
  19. ^ "Distribution XML Reference". developer.apple.com. Retrieved 2017-05-23.
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