3.7. System Calls
System calls are interfaces used by user programs to have the kernel perform a specific function on behalf of the calling thread or process. Because some system calls on UNIX platforms are more operating system-specific, they may not be available on Linux. When this happens, a wrapper call may have to be implemented on the Linux side.
A list of system calls in Linux can be located at /usr/include/asm/unistd.h. Tables that give a side-by-side comparison between Linux and a different operating system such as Solaris and HP-UX are also presented in the appendix of this book.