The important thing to know about a system call is its prototype. You need to know how many arguments, their types, and the function return type. There are six macros that make the actual call into the system easier. System calls are not required to return only positive or negative error codes. You need to read the source to be sure how it will return errors.
Some system calls, such as mmap , require more than five arguments.
These are handled by pushing the arguments on the stack and passing a pointer to the block of arguments. The 4.3 and 4.4 distributions of Berkeley Unix. 4.4BSD was upward-compatible from 4.3. V7 Version 7, the ancestral Unix from Bell Labs. This document was created by man2html , using the manual pages.