> For the complete documentation index, see [llms.txt](https://davidjosearaujo.gitbook.io/notes-miect/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://davidjosearaujo.gitbook.io/notes-miect/sistemas-de-operacao/processes-in-unix-linux/execution-of-a-c-c++-program.md).
# Execution of a C/C++ program
## *atexit*
The **atexit** function allows to register a function to be called at the program’s normal termination*.*
They are called in reverse order relative to their register*.*
## Command line arguments and environment variables
**argv** is an array of strings.
**argv\[0]** is the program reference.
**env** is an array of strings, each representing a variable, in the form **name-value** pair.
**getenv** returns the value of a variable name.
## Address space of a Unix process
