A. 编写一段c语言程序，使进程1创建出2 3 4 子进程，子进程3创建孙进程5 ，5在创建出重孙6
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main()
{
int pid1, pid2, pid3, pid4, pid5, pid6;
pid1 = getpid();
printf("PID = %d\n", pid1);
pid2 = fork();
if (pid2 == 0)
{
printf("PID = %d, Parent PID = %d\n", getpid(), getppid());
sleep(30);
exit(0);
}
pid3 = fork();
if (pid3 == 0)
{
printf("PID = %d, Parent PID = %d\n", getpid(), getppid());
pid5 = fork();
if (pid5 == 0)
{
printf("PID = %d, Parent PID = %d\n", getpid(), getppid());
pid6 = fork();
if (pid6 == 0)
{
printf("PID = %d, Parent PID = %d\n", getpid(), getppid());
sleep(30);
exit(0);
}
sleep(30);
exit(0);
}
sleep(30);
exit(0);
}
pid4 = fork();
if (pid4 == 0)
{
printf("PID = %d, Parent PID = %d\n", getpid(), getppid());
sleep(30);
exit(0);
}
sleep(30);
return 0;
}
每一个进程都会在退出前 sleep 30秒，从而保证能够用 ps 看到，
编译 gcc testpid.c -o testpid
然后执行，可以看到
PID = 24913
PID = 24914, Parent PID = 24913
PID = 24916, Parent PID = 24913
PID = 24915, Parent PID = 24913
PID = 24917, Parent PID = 24915
PID = 24918, Parent PID = 24917
ps -ef 的结果
24913 24582 0 11:29 pts/19 00:00:00 ./testpid
24914 24913 0 11:29 pts/19 00:00:00 ./testpid
24915 24913 0 11:29 pts/19 00:00:00 ./testpid
24916 24913 0 11:29 pts/19 00:00:00 ./testpid
24917 24915 0 11:29 pts/19 00:00:00 ./testpid
24918 24917 0 11:29 pts/19 00:00:00 ./testpid