Open Source Programming

• Open source programming: 1983, Richard Stallman started the GNU Project (GNU = Gnu is not Unix), a software movement to provide free and quality software.
• 1984 - Stallman started to write the GNU C compiler (gcc), considered as one of the most efficient and robust compilers ever created.
• Open source programs are released under the GNU General Public License.

Linux History

• Minix, the first open source operating system, written by Andrew S. Tanenbaum in C, about 12000 lines of code.
• 1991, first Linux kernel written in C by Linus Torvalds, University of Helsinki, Finland. First message about it posted on August 25, first release in September.
• It was developed with the contribution of many programmers around the world.
• It is functionally similar to Unix (a clone).

Linux Development

• 1993 - FreeBSD 1.0 (Berkley Unix)
• 1994 - RedHat Linux is introduced.
• 1999 - Linux available for PowerPC (Apple)
• Now - adopted by many companies and most universities, third world countries.
• Standard for parallel and high performance computing (Beowulf clusters).
• Available for most computers, including PDA, supports graphical user interfaces, networking, and has many applications.

Why Linux

• It's free! - the source code is also available and anybody can write their own Linux as long as they include the source code in the distribution.
• Most users consider it a more stable and reliable OS than Windows.
• It's an alternative to Microsoft's dominance of the software market.
• It is multi-tasking, multi-user. Good support of multiple CPUs.
• Many utilities and APIs are now included in most distributions, like the g++ compiler, OpenGL, MPI, pthreads, etc.
• MacOS has now an integrated shell (terminal) and can run X11 applications which are Unix and Linux specific.

Linux Components

• The kernel - the core of the OS that controls the resources.
• A hierarchical file system (FHS)
• Shells - applications that interpret the commands from the user. They are active in the textual mode or terminal mode. Shells can also execute script files. Examples: bash, tcsh, zsh, sh, etc.
• Graphical interfaces - the X window system. Desktop interfaces: Gnome, KDE, fvwm, etc. Specific libraries: X11, gtk-glib-gnome, Qte, etc.