linux中fork()和vfork()函数的使用和区别
fork()的使用如下:
</pre><pre name="code" class="cpp">#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int glob = 6;
char buf[] = "a write to stdout\n";
int main()
{
int var;
pid_t pid;
FILE *fp = NULL;
fp=fopen("./1.log", "aw");
fwrite(buf, sizeof(buf), 1, fp);
pid = fork();
if(pid < 0)
printf("err\n");
if(pid == 0)
{
glob++;
printf("child: %d\n", glob);
}
else
{
sleep(3);
printf("parent: %d\n", glob);
}
fclose(fp);
exit(0);
}
<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">由于fork使子进程不继承父进程的资源,所以,在子进程中改变glob的值,并不影响,父进程的glob的值</span>
输出结果时在1.log中出现两行buf的文字
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int glod = 6;
char buf[] = "a write to stdout\n";
int main()
{
pid_t pid;
FILE *fp = NULL;
fp=fopen("./1.log", "aw");
fwrite(buf, sizeof(buf), 1, fp);
pid = vfork();
if(pid< 0)
{
printf("err.\n");
}
if(pid == 0)
{
glod++;
printf("child: %d\n", glod);
// _exit(0);
exit(0);
}
else
{
printf("parent: %d\n", glod);
}
exit(0);
}
在子进程中改变glod值,父进程也随之改变
1.log中只出现一行buf内容