Linux Command Fork ()

Linux Command Fork ()-General Linux technology-Linux programming and kernel information. The following is a detailed description. Fork is the meaning of fork. That is to say, it will play a "Forks" role. In Unix operating systems, it is often used to generate new processes. So what will happen when fork is called? First, the parent process shares a code segment with the child process, and the data segment and stack segment are copied to the child process by the parent process. When the generation is complete, the parent process and the child process are already two independent processes, especially the data segment, which are separated (although they are the same at the beginning, after their respective operations, is Different), does not share data.

If fork is successful, the return value of fork in the child process is 0, and the return value of fork in the parent process is the process number of the child process. If fork is not successful, the parent process returns an error. In this program code, we may have misunderstandings. When we see the if-else structure, we will divide it into three segments: pid <0, pid = 0 and pid> 0. When a certain condition is met, a program will be implemented. But this is not the case.

We can think that if there is no wait function, the parent process and the child process run in parallel and the steps are consistent (the actual operating system depends on who runs first ). After fork, they perform different work. The returned pid is only used to distinguish between parent and child processes.