Unix/Linux to Windows: Migration, Porting & Using

by Rodney Ruddock

The Interix / SUA Solution

Interix, Service for Unix (SFU) and Subsystem for Unix-based Applications (SUA) provide support for Unix or Linux applications being used on Windows systems. Interix is the Unix-like subsystem that runs as a peer to the Windows subsystem on the Windows OS. Interix is a component of SFU and is the core of SUA. The Subsystem for Unix-based Applications is included as part of the Windows OS distribution in servers W2K3/R2, W2K8 and W2K8/R2 plus the workstation releases Vista Ultimate and Vista Enterprise. Eariler releases of Windows (XP and W2K3) can use SFU.

You may be working in a multiple OS environment or have been told that you must move your applications to Windows from a Unix or Linux system. The work involved porting or migrating source code and scripts is usually much higher and will take longer than anticipated if the target is Win32. By using Interix/SUA the effort is dramatically reduced because the target is "just another Unix platform".

The advantages of using Interix/SUA over other solutions can be highlighted with a few of the key factors that matter to users (summarized):

Speed and performance
Complete Unix environment
Root powers for super-user
Case-sensitive filesystem
Unix/Posix signal support
User database access integrated with Active Directory (AD)
No reliance on .NET
IP not tied to GPL

Many people are also comforted by the fact that it is Microsoft supported around the world. This means people with support contracts can get help through their regular channels. Support is also available through the SUA Community forums here at this site as well.

Speed and Performance

Over many years the Performance of Interix has been improved even when it was already ahead of the alternatives. After all, when do users not want better performace?! A central part of the better performance is that Interix/SUA is a subsystem. This closer relationship to the Windows OS kernel means functionality and fidelity of Unix is not an emulation. For example in the last performance testing I did the fork/exec test was 5 times better for Interix/SUA. The write performace was 3.7 times faster than one of the alternatives.

Complete Unix Environment

By having all of the standard shells, utilities and daemons available the working environment for your aplications and your developers a migration or porting is made much easier. Familiar ways of solving a problem can still be done the same way giving the same result. The familiar environment also means that there will not be new unexpected conditions for you, your programs or scripts to handle.

Root-like Powers

One of the big advantages of a Unix environment is the power that "root" has. This can help you solve many problems in a straight-forward manner. This can range from small actions such as changing ownership on a file to having an application 'setuid' to run as a particular user. On Interix/SUA the local and domain Administrator are set as special accounts that have the "root" powers without extending this power to the Win32 system. Executable files can be 'setuid' just like on a Unix, BSD or Linux system.

Unix/Posix Signal Support

Full Unix/Poisx signal support is very important for the fidelity of program behavior when migrating/porting source code. The delivery of all signals in a correct manner is not always supported by alternative -- some only work with a subset of signals. If you must migration Unix code to Win32 then very significant source code changes will be needed. Even after these changes the behavior can no longer be identical to a Unix or Linux system. Interix/SUA has all of the Unix/Posix signal support and the behavior remains unchanged.

User database with AD

Interix/SUA accesses and sets user and group information through Active Directory (AD). There is no cacheing to a "passwd" file that will be rapidly out of date. When you work in an environment of 10,000 users it is impossible to keep synchronizing special files to AD and maintain accuracy. By not working with AD directly security difficulties may arise too.

No .NET

With no reliance on .NET Interix/SUA runs on all versions of Windows Server. This means your scripts and programs work on all your server systems. It also means a lower overhead for resources when applications are running.

IP (Intellectual Property) not tied to GPL

All of the Microsoft distributed libraries contain no GPL code. This means any programs you migrate, port or develop will not be tied to the GPL. Many people are aware, and many not, that if your application uses a GPL library, such as readline, then your application must be placed under the GPL if you distribute it. This can have consequences for businesses, retailers and secure sites.

Of the 400 utilities that come with Interix/SUA only 3 or 4 are GNU based. GNU based utilities, though under GPL, do not force users to use the GPL. The same holds true for applications built with the 'gcc' suite of tools.

What's Available with Interix, SUA & Subsystem for Unix-based Applications (SUA)

A more detailed, stand-alone article is the proper way to treat this part of the topic. But we'll give brief coverage to touch on the key points.

From Microsoft Interix/SUA comes with over 400 utilities and daemons that are common to the Unix/Linux base of utilities. This imcludes the manual pages, system configurations files, shells, scripts and tools. By adding both SDK's support is added for using Microsoft's Visual C (MSVC) compiler and for using GNU's gcc suite to build and debug programs. The SDK portion includes the API manual pages as well as additional tools for building and using shared libraries or DSO's.

The SUA Community web site has been providing additional software for Interix and SUA for over 7 years now. The packages are available individually (pick what you want) or as pre-built bundles (collections of packages). These packages help augment what comes from Microsoft. This includes programs that Unix/Linix frequently use such as OpenSSH for ssh & sftp, bash as a shell, and Apache. For developers additional development libraries are available too such as OpenSSL, glib, BIND and Qt. Updates to the Microsoft utilities are available as well that have additional functionality or enhanced options -- for example, long options. There is also a special library, libport, to help when porting source code.

Another site that builds over the Microsoft base installation is the Debian/Interix site. It uses the Debian versions of software (GNU based).

Interix / SUA in Use

Recently we held a survey of SUA Community users that over 560 people were gracious enough to take the time to answer. This is the most comprehensive survey to date of Interix, SFU and SUA users.

People and companies using Interix/SUA vary from individuals though small businesses to very large corporations (100,000+ employees). The types of uses vary from aircraft design, to POS, to print management, Universities, product manufacturing, Governments (several), R&D and Big Oil with the large users. In the middle to small range Consultants, churches and R&D use Interix/SUA to "get the job done".

Many of these users are involved with HPC or similar applications where speed is important (you want the answer in two days or eight days?). These users benefit from the performance that Interix/SUA comes with plus the updated, faster libm math library from SUA Community (it's free).

Conclusion

Interix/SUA is a strong alternative to use when you become involved with a Unix/Linux migration porting or code use to Windows OS. If there are specific questions you can ask in the SUA Community Forums or send me e-mail.

Unix/Linux to Windows: Migration, Porting & Using by Rodney Ruddock The Interix / SUA Solution Interix, Service for Unix (SFU) and Subsystem for Unix-based Applications (SUA) provide support for Unix or Linux applications being used on Windows systems. Interix is the Unix-like subsystem that runs as a peer to the Windows subsystem on the Windows OS. Interix is a component of SFU and is the core of SUA. The Subsystem for Unix-based Applications is included as part of the Windows OS distribution in servers W2K3/R2, W2K8 and W2K8/R2 plus the workstation releases Vista Ultimate and Vista Enterprise. Eariler releases of Windows (XP and W2K3) can use SFU. You may be working in a multiple OS environment or have been told that you must move your applications to Windows from a Unix or Linux system. The work involved porting or migrating source code and scripts is usually much higher and will take longer than anticipated if the target is Win32. By using Interix/SUA the effort is dramatically reduced because the target is "just another Unix platform". The advantages of using Interix/SUA over other solutions can be highlighted with a few of the key factors that matter to users (summarized): Speed and performance Complete Unix environment Root powers for super-user Case-sensitive filesystem Unix/Posix signal support User database access integrated with Active Directory (AD) No reliance on .NET IP not tied to GPL Many people are also comforted by the fact that it is Microsoft supported around the world. This means people with support contracts can get help through their regular channels. Support is also available through the SUA Community forums here at this site as well. Speed and Performance Over many years the Performance of Interix has been improved even when it was already ahead of the alternatives. After all, when do users not want better performace?! A central part of the better performance is that Interix/SUA is a subsystem. This closer relationship to the Windows OS kernel means functionality and fidelity of Unix is not an emulation. For example in the last performance testing I did the fork/exec test was 5 times better for Interix/SUA. The write performace was 3.7 times faster than one of the alternatives. Complete Unix Environment By having all of the standard shells, utilities and daemons available the working environment for your aplications and your developers a migration or porting is made much easier. Familiar ways of solving a problem can still be done the same way giving the same result. The familiar environment also means that there will not be new unexpected conditions for you, your programs or scripts to handle. Root-like Powers One of the big advantages of a Unix environment is the power that "root" has. This can help you solve many problems in a straight-forward manner. This can range from small actions such as changing ownership on a file to having an application 'setuid' to run as a particular user. On Interix/SUA the local and domain Administrator are set as special accounts that have the "root" powers without extending this power to the Win32 system. Executable files can be 'setuid' just like on a Unix, BSD or Linux system. Unix/Posix Signal Support Full Unix/Poisx signal support is very important for the fidelity of program behavior when migrating/porting source code. The delivery of all signals in a correct manner is not always supported by alternative -- some only work with a subset of signals. If you must migration Unix code to Win32 then very significant source code changes will be needed. Even after these changes the behavior can no longer be identical to a Unix or Linux system. Interix/SUA has all of the Unix/Posix signal support and the behavior remains unchanged. User database with AD Interix/SUA accesses and sets user and group information through Active Directory (AD). There is no cacheing to a "passwd" file that will be rapidly out of date. When you work in an environment of 10,000 users it is impossible to keep synchronizing special files to AD and maintain accuracy. By not working with AD directly security difficulties may arise too. No .NET With no reliance on .NET Interix/SUA runs on all versions of Windows Server. This means your scripts and programs work on all your server systems. It also means a lower overhead for resources when applications are running. IP (Intellectual Property) not tied to GPL All of the Microsoft distributed libraries contain no GPL code. This means any programs you migrate, port or develop will not be tied to the GPL. Many people are aware, and many not, that if your application uses a GPL library, such as readline, then your application must be placed under the GPL if you distribute it. This can have consequences for businesses, retailers and secure sites. Of the 400 utilities that come with Interix/SUA only 3 or 4 are GNU based. GNU based utilities, though under GPL, do not force users to use the GPL. The same holds true for applications built with the 'gcc' suite of tools. What's Available with Interix, SUA & Subsystem for Unix-based Applications (SUA) A more detailed, stand-alone article is the proper way to treat this part of the topic. But we'll give brief coverage to touch on the key points. From Microsoft Interix/SUA comes with over 400 utilities and daemons that are common to the Unix/Linux base of utilities. This imcludes the manual pages, system configurations files, shells, scripts and tools. By adding both SDK's support is added for using Microsoft's Visual C (MSVC) compiler and for using GNU's gcc suite to build and debug programs. The SDK portion includes the API manual pages as well as additional tools for building and using shared libraries or DSO's. The SUA Community web site has been providing additional software for Interix and SUA for over 7 years now. The packages are available individually (pick what you want) or as pre-built bundles (collections of packages). These packages help augment what comes from Microsoft. This includes programs that Unix/Linix frequently use such as OpenSSH for ssh & sftp, bash as a shell, and Apache. For developers additional development libraries are available too such as OpenSSL, glib, BIND and Qt. Updates to the Microsoft utilities are available as well that have additional functionality or enhanced options -- for example, long options. There is also a special library, libport, to help when porting source code. Another site that builds over the Microsoft base installation is the Debian/Interix site. It uses the Debian versions of software (GNU based). Interix / SUA in Use Recently we held a survey of SUA Community users that over 560 people were gracious enough to take the time to answer. This is the most comprehensive survey to date of Interix, SFU and SUA users. People and companies using Interix/SUA vary from individuals though small businesses to very large corporations (100,000+ employees). The types of uses vary from aircraft design, to POS, to print management, Universities, product manufacturing, Governments (several), R&D and Big Oil with the large users. In the middle to small range Consultants, churches and R&D use Interix/SUA to "get the job done". Many of these users are involved with HPC or similar applications where speed is important (you want the answer in two days or eight days?). These users benefit from the performance that Interix/SUA comes with plus the updated, faster libm math library from SUA Community (it's free). Conclusion Interix/SUA is a strong alternative to use when you become involved with a Unix/Linux migration porting or code use to Windows OS. If there are specific questions you can ask in the SUA Community Forums or send me e-mail.
© 2008. 2009 Interop Systems Inc.