Linux Past Life __linux

Unix
The predecessor of Unix was Multics, Bell Labs was involved in the development of the operating system, but Bell Labs decided to give up the plan because of the slow pace. Bell Labs engineers, Thompson and Ricky, developed Unix at the time. The first version of Unix was written in PDP-7 assembly language. And in 1971 jointly invented the C language. In the 1973 Thompson and Ricky rewrote Unix in C to form a third edition of Unix.

Gnu
UNIX is the name of a widely used commercial operating system. All the software on it is proprietary software and needs to be charged. GNU is going to implement the interface standards for UNIX systems, just like proprietary software on UNIX, but free of charge.
Like what:
Emacs.
GNU C Compile GCC
GNU C Library GLIBC
Bash Shell

GPL GNU general public License
To ensure that GNU software is free to "use, copy, modify, and publish," All GNU software has an agreement to authorize all rights to anyone without any restriction from others.

FSF (free Software Foundation) Freedom Software Foundation.
Provide technical, legal and financial support for the GNU project. Although the GNU program is largely voluntary and unpaid, the FSF sometimes hires programmers to help with writing. As the GNU program began to succeed, some commercial companies began to intervene in development and technical support. One of the best-known is the Cygnus Solutions, which was later merged by Red Hat.

Linux
Minix: Similar to the UNIX system, the gas follows the Minix system to write its own kernel Linux 0.02. Also, to accommodate some Unix-run software that runs on Linux, modify the Linux kernel to refer to the standard POSIX specification. Soon Linux and Unix are compatible to share all the software.
POSIX represents the Portable Operating system interface (Portable operating system Interface, abbreviated to POSIX), and the POSIX standard defines the interface standards that the operating system should provide for the application. is the general name of a series of API standards that IEEE defines for software to run on a variety of UNIX operating systems.

Linux Distributions
The advent of Linux has completely freed GNU project developers because they do not have their own kernel programs before Linux, and their free software can only run on UNIX.
To allow users access to Linux, many commercial companies make Linux distribution the kernel (Kernel) and running GNU Software (softwares) and their own creative tool programs (tools)
At present, Linux distributions is mainly divided into two major systems, one is the use of RPM to install the software system, including Red Hat,fedora. There is also a system for installing software using Debian dpkg, including Debian,ubuntu.