from Plan 9, like the UTF-8 character encoding of Unicode, have been implemented in other operating systems. Unix-like operating systems such as Linux have implemented 9P2000, Plan 9's protocol for accessing remote files, and have adopted features of rfork, Plan 9's process creation mechanism. Additionally, in Plan 9 from User Space, several of Plan 9's applications and tools, including the sam and acme editors, have been ported to Unix and Linux systems and have achieved some level of popularity. Several projects seek to replace the GNU operating system programs surrounding the Linux kernel with the Plan 9 operating system programs. The 9wm window manager was inspired by 8½, the older windowing system of Plan 9; wmii is also heavily influenced by Plan 9. In computer science research, Plan 9 has been used as a grid computing platform and as a vehicle for research into ubiquitous computing without middleware. In commerce, Plan 9 underlies Coraid storage systems. However, Plan 9 has never approached Unix in popularity, and has been primarily a research tool: Other factors that contributed to low adoption of Plan 9 include the lack of commercial backup, the low number of end-user applications, and the lack of device drivers. Plan 9 proponents and developers claim that the problems hindering its adoption have been solved, that its original goals as a distributed system, development environment, and research platform have been met, and that it enjoys moderate but growing popularity. Inferno, through its hosted capabilities, has been a vehicle for bringing Plan 9 technologies to other systems as a hosted part of heterogeneous computing grids. Several projects work to extend Plan 9, including 9atom and 9front. These forks augment Plan 9 with additional hardware drivers and software, including an improved version of the Upas e-mail system, the Go compiler, Mercurial version control system support (and now also a git implementation), and other programs. Plan 9 was ported to the Raspberry Pi single-board computer. The Harvey project attempts to replace the custom Plan 9 C compiler with GCC, to leverage modern development tools such as GitHub and Coverity, and speed up development. Since Windows 10 version 1903, the Windows Subsystem for Linux implements the Plan 9 Filesystem Protocol as a server and the host Windows operating system acts as a client. Derivatives and forks Inferno is a descendant of Plan 9, and shares many design concepts and even source code in the