我该如何转换:
FILE *f;
char in_buffer[80];
f=popen("command","r");
fgets(in_buffer,sizeof(in_buffer),f)
不使用
popen()
,但只使用pipe()
或其他指令? 最佳答案
这是我的简单实现,注释解释了正在做的事情。
#include <unistd.h>
#include <stdio.h>
FILE *
my_popen (const char *cmd)
{
int fd[2];
int read_fd, write_fd;
int pid;
/* First, create a pipe and a pair of file descriptors for its both ends */
pipe(fd);
read_fd = fd[0];
write_fd = fd[1];
/* Now fork in order to create process from we'll read from */
pid = fork();
if (pid == 0) {
/* Child process */
/* Close "read" endpoint - child will only use write end */
close(read_fd);
/* Now "bind" fd 1 (standard output) to our "write" end of pipe */
dup2(write_fd,1);
/* Close original descriptor we got from pipe() */
close(write_fd);
/* Execute command via shell - this will replace current process */
execl("/bin/sh", "sh", "-c", cmd, NULL);
/* Don't let compiler be angry with us */
return NULL;
} else {
/* Parent */
/* Close "write" end, not needed in this process */
close(write_fd);
/* Parent process is simpler - just create FILE* from file descriptor,
for compatibility with popen() */
return fdopen(read_fd, "r");
}
}
int main ()
{
FILE *p = my_popen ("ls -l");
char buffer[1024];
while (fgets(buffer, 1024, p)) {
printf (" => %s", buffer);
}
fclose(p);
}
笔记:
thir代码只支持
"r"
模式。实现其他模式,即popen
模式,留给读者作为练习。本例中使用的系统功能可能会失败-错误处理留给读者作为练习。
"w"
的实现留给读者作为练习-请参见pclose
、close
和waiptid
。如果你想了解真正的弹劾案,你可以调查OSX、GNU glibc和OpenSolaris等的来源。
希望这有帮助!