Linux System Calls and their Numbers
If you ever want to refresh numeric IDs of specific system calls in your Linux system it’s easy to do by inspecting some of the standard Linux header (include) files.
In operating systems, Linux/Unix included, system calls are a special set of procedures that regular programs (usespace processes) for working with hardware, internal OS functionality, all sorts of cummunication and process management, and everything security enhanced. Such procedures interface with OS kernel that verifies validity of a system call and them executes it within kernel space, then returning something back.
In Linux (I’m using CentOS server for this post) you’ll most likely find two files with system call definitions: 32-bit version and 64-bit version:
Both have system calls lists like this (that’s the unistd_32.h file):