实现功能，当父进程检测到输入为1的时候，创建子进程把配置文件的字段值修改调。
config.txt的内容
SOEED=3
LENG=9
SCORE=9
LEVEL=5
没有运用exec族函数
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
int main()
{
pid_t pid;
int data=10;
while(1){
printf("please input a data\n");
scanf("%d",&data);
if(data==1){
pid=fork();
if(pid>0)
{
wait(NULL);
}
else if(pid==0){
int fdSrc;
char *readBuf=NULL;
fdSrc=open("config.txt",O_RDWR);
int size=lseek(fdSrc,0,SEEK_END);
lseek(fdSrc,0,SEEK_SET);
readBuf=(char *)malloc(sizeof(char)*size+8);
int n_read=read(fdSrc,readBuf,size);
char *p= strstr(readBuf,"LENG=");
if(p==NULL){
printf("not found\n");
exit(-1);
}
p=p+strlen("LENG=");
*p='5';
lseek(fdSrc,0,SEEK_SET);
int n_write= write(fdSrc,readBuf,strlen(readBuf));
close(fdSrc);
exit(0);
}
}
else{
printf("wait, do nothing\n");
}
}
return 0;
}
changData.c中的内容
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
int main(int argc,char **argv)
{
int fdSrc;
char *readBuf=NULL;
if(argc!=2){
printf("pararm errpr\n");
exit(-1);
}
fdSrc=open(argv[1],O_RDWR);
int size=lseek(fdSrc,0,SEEK_END);
lseek(fdSrc,0,SEEK_SET);
readBuf=(char *)malloc(sizeof(char)*size+8);
int n_read=read(fdSrc,readBuf,size);
char *p= strstr(readBuf,"LENG=");
if(p==NULL){
printf("not found\n");
exit(-1);
}
p=p+strlen("LENG=");
*p='5';
lseek(fdSrc,0,SEEK_SET);
int n_write= write(fdSrc,readBuf,strlen(readBuf));
close(fdSrc);
return 0;
}
运用exec族函数
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
int main()
{
pid_t pid;
int data=10;
while(1){
printf("please input a data\n");
scanf("%d",&data);
if(data==1){
pid=fork();
if(pid>0)
{
wait(NULL);
}
else if(pid==0){
execl("./changData","chuangData","config.txt",NULL);
}
}
else{
printf("wait, do nothing\n");
}
}
return 0;
}