Unix kernel
unix.
Programming, its first major application was UNIX.
There is very little difference in the C compiler between Unix and Linux; in some cases (the gcc compiler) it is the same. The differences come in when using system calls; some system calls do not exist in Unix or Linux, although most do. The program I work on compiles the same way (for the most part) between all commercial versions of Unix and several variants of Linux. In other words, the code is fairly portable across platforms.
C/C++ is used to write system softwares. The whole of UNIX operating system is written in C language.
Unix came first; Linux is a clone of the Unix Operating System.
Unix.
The C language was created for a specific purpose: to design the UNIX operating system (which is used on many computers).
Unix kernel
The Unix operating system. The first versions of the Unix operating system were written in the "B" language, and later written in "C", which was invented in order to develop Unix on the PDP-11 machine.
You can debug C programs using gdb on Unix.
There is no such thing as 'unix C++'.
UNIX was programmed in C.
unix.
The C language has implementations for all popular platforms, including Unix.
Programs have existed since Unix was conceived: in fact, the operating system is no more than a kernel and user-space programs! Unix was first released in 1969, and along came with supplemental programs distributed as part of the original Unix operating system at AT&T Bell Laboratories.
The C programming language was originally created for Unix. Unix, and most other Unix-like systems such as Linux, are written almost entirely in C.