C 紫禁城 Fork(), execvp 是个啥？好难找到资料啊

搜了搜比较有价值的是这一篇

https://ece.uwaterloo.ca/~dwharder/icsrts/Tutorials/fork_exec/

#include <stdio.h>

/* This program forks and and the prints whether the process is
 *   - the child (the return value of fork() is 0), or
 *   - the parent (the return value of fork() is not zero)
 *
 * When this was run 100 times on the computer the author is
 * on, only twice did the parent process execute before the
 * child process executed.
 *
 * Note, if you juxtapose two strings, the compiler automatically
 * concatenates the two, e.g., "Hello " "world!"
 */

int main( void ) {
	char *argv[3] = {"Command-line", ".", NULL};

	int pid = fork();

	if ( pid == 0 ) {
		execvp( "find", argv );
	}

	/* Put the parent to sleep for 2 seconds--let the child finished executing */
	wait( 2 );

	printf( "Finished executing the parent process\n"
	        " - the child won't get here--you will only see this once\n" );

	return 0;
}

Stack Overflow 上很少有人讨论这个话题，有大佬能发一下资料吗