linux c语言 使用system echo把变量输出到文件中

#include
#include
#include

int main(void)
{
char *url = "asdfasdfasdf";
system("echo $url > /home/ylk/Desktop/1.txt");
printf("\nurl=%s\n", url);
return 0;
}

结果不能把字符串写到1.txt中，怎么修改可以写进去呢？

参考这个试试：http://zhidao.baidu.com/link?url=6d0quW4LRR6A0Kbz4EzFU8HLoPyr2wXmfCK9MBxGIBSF0WX8BD_Lk-5H9d42Foz9To1RfrMze3mlKtxzQrCH6EIlc_Bh9KgCuHMNsoeDnB_

system("echo asdfasdfasdf"> /home/ylk/Desktop/1.txt");

或者

char buffer[128];
char *url = "asdfasdfasdf";
sprintf(buffer, "echo "%s >  /home/ylk/Desktop/1.txt", url);
system(buffer);