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README BASIC SHELL

BASIC SHELL FUNCTIONS

getpid()

Takes in parametres void and returns the pid of the child of the current process.

            
			    #include 
			    #include 
			    /*The unistd.h is the liberary in which the function getpid() exists*/
			    int main()
			    {
			        pid_t pid;
			        pid = getpid();
			        printf("%d", pid);
			        return (0);
			    }
  • Getpid function returns a value of type pid_t, which is integer type. This type is defined in sys/types.h, but since it is alse defined in unistd.h then only called that liberary.
  • Is a system call, which means that it communicates with the kernel to retrieve the child's process ID.
  • The PID is assigned to the process by the operating system when the process is created and remains constant throughout the lifetime of the process.
  • The PID value is usually positive, with values greater than 1. The value of 0 is reserved for the scheduler process, while -1 is used to indicate an error, and -2 is used to indicate that the PID is not known (for example, if the process has terminated and its PID has been reassigned to a new process).