In general, no, it is not difficult at all. As long as you stick to the POSIX (and other open standards) and use a conformant compiler for the software there shouldn't be any problem in porting software.
I do it all the time - from Linux to Unix, or Unix to Linux, makes no difference. In fact, a lot of common software is cognizant of the actual Operating System at compile time and will take care of the differences (if there are any).
Linux is not illegal. Linux is a free, public license software modeled on Unix.
Unix and Linux
Unix, Linux, windows and compilers etc.
No, but Linux is based on Unix since Linux is a Unix clone.
Because Linux was modeled after Unix, and designed to be a suitable free replacement. Windows is targeted at a slightly different market, and was primarily designed to be operated using a GUI, not the command line.
Because Linux was modeled after Unix, and designed to be a suitable free replacement. Windows is targeted at a slightly different market, and was primarily designed to be operated using a GUI, not the command line.
Because Linux was modeled after Unix, and designed to be a suitable free replacement. Windows is targeted at a slightly different market, and was primarily designed to be operated using a GUI, not the command line.
Linux was introduced in 1991
No. Linux, like Unix, is designed to be a multi-user system.
The idea behind Linux was to create an operating system that could run UNIX software, but would be free.
POSIX is a standard designed to ensure API compatibility between Unix and Unix-like operating systems operating systems. Linux implements most of the POSIX standard, but is not certified as such.
Linux is an open system, Unix is not.