C Compiler
On POSIX-compliant systems, the C compiler is called c89. Historically, the C compiler was simply called cc. Over the years, different vendors have sold UNIX-like systems with C compilers with different facilities and options, but often still called cc.
When the POSIX standard was prepared, it was impossible to define a standard cc command with which all these vendors would be compatible. Instead, the committee decided to create a new standard command for the C compiler, c89. When this command is present, it will always take the same options, independent of the machine.
On Linux systems that do try to implement the standards, you might find that any or all of the commands c89, cc, and gcc refer to the system C compiler, usually the GNU C compiler, or gcc. On UNIX systems, the C compiler is almost always called cc.
We’ll be using gcc because it’s provided with Linux distributions and because it supports the ANSI standard syntax for C. If you ever find yourself using a UNIX system without gcc, we recommend that you obtain and install it. You can find it at http://www.gnu.org. Wherever we use gcc in the book, simply substitute the relevant command on your system.