At that time AT&T company was a controlled monopoly, so he could not sell computer software. He gave it to the government and universities unconditionally with the source code, if they want, they can manipulate them. Coming in the late 1980's, Unix became the most popular, powerful, and stable operating system.
There was some weak points of unix - it was difficult to understand and run. Andrew S. Tanenbaum is a computer science professor in Amsterdam. He wrote a program called Minix to help it. There were some drawbacks in this too. Linus Torvalds was a student of computer science at Helsinki University of Finland. They wrote a program to remove the weak points of Minix which was later called 'Linux of Unix' or 'Linux'. Its first core or kernel was posted in the Internet in 1991. By then Richard Stallman's GNU project had started. Linus Torvalds has taken lot of programs in his Linux.
Therefore, Richard Stallman says that it should say GNU-Linux. But this name may not have been possible due to being prolonged. But this does not mean that the GNU Project does not have the hand in Linux's success. Without the GNU Project, Linux was not possible.