Porting a C# Windows application to Linux

I own a Windows application. To expand our customer base, we need to create a Linux edition. In anticipating the demand, we previously decided to place the majority of logics in a few .net standard libraries and this is a big paid-off. However, there are still a few things we need to do so that the same code would work on both Windows and Linux.

1. Path separator is different between Windows and Linux. Windows uses “\” as separator while Linux uses “/” as separator. The solution is to always use Path.Combine to concatenate paths. Similarly, use Path.GetDirectoryName and Path.GetFileName to split the paths.
2. Linux file system is case sensitive. The solution is to be very consistent with path names and always use constants when a path is used in multiple places.
3. In text files, Windows uses \r\n to end lines while Linux uses \r. The solution is to use TextReader.ReadLine and TextWriter.WriteLine. TextReader.ReadLine reads Windows text files correctly on Linux and vice versa. If we have to face line-ending characters explicitly, use Environment.NewLine.
4. Different locations for program files and program data. Windows by defaults store programs in “c:\Program Files” folder and store program data in “c:\ProgramData”. The exact location can be determined from the %ProgramFile% and %ProgramData% environment variables. Linux, in contrast, has a different convention and one often install programs under /opt and write program data under /var. For complete reference, see: http://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/. This is an area we have to branch the code and detect operating system using RuntimeInformation.IsOSPlatform.
5. Lack of registry in Linux. The solution is to just use configuration files.
6. Windows has services while Linux has daemon. The solution is to create a Windows Service application on Windows and create a console application on Linux. RedHat has a good article on creating Linux daemon in C#: https://developers.redhat.com/blog/2017/06/07/writing-a-linux-daemon-in-c/. For addition information on Systemd, also see: https://www.digitalocean.com/community/tutorials/understanding-systemd-units-and-unit-files.
7. Packaging and distribution. Windows application are usually packaged as msi or Chocolatey package. Linux applications are usually packaged as rpm. This will be the subject of another blog post.