Linux下C語言使用popen獲取一個文件的內容小實例

#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>
#include <unistd.h>

void printpwd(struct passwd *pwd)
{
	printf("name:%s\n", pwd->pw_name);
	printf("passwd:%s\n", pwd->pw_passwd);
	printf("uid:%u\n", pwd->pw_uid);
	printf("gid:%u\n", pwd->pw_gid);
	printf("gecos:%s\n", pwd->pw_gecos);
	printf("dir:%s\n", pwd->pw_dir);
	printf("shell:%s\n", pwd->pw_shell);
}
int main(void)
{
	FILE *pf;
	char filepath[128] = {0};
	char readcmd[128] = {0};
	struct passwd *pwd;
	char buff[24] = {0};

	/*獲取當前用戶的信息*/
	pwd = getpwuid(getuid());
	printpwd(pwd);//打印

	/*根據用戶名組建文件路徑*/
	snprintf(filepath, 128, "/home/%s/test.conf", pwd->pw_name);

	/*組建shell命令*/
	snprintf(readcmd, 128, "cat %s", filepath);

	/*判斷文件是否存在，如果不存在則創建，並賦予初始值爲hello world*/
	if(access(filepath, F_OK) == -1)
	{
		popen("echo 'hello world' > ~/test.conf", "r");
	}

	/*通過popen運行shell命令，並通過返回的文件描述符讀取文件中的內容*/
	if((pf = popen(readcmd, "r")) != NULL)
	{
		if(fgets(buff, 24, pf) != NULL)
			printf("content in %s is:%s", filepath, buff);
		pclose(pf);//這裏不能用fclose()!
		pf = NULL;
	}


	return 0;
}




編譯運行效果：
<img src="https://img-blog.csdn.net/20160707133820323?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />