Linux：编写一个“控制”C 程序一个贝壳
假设我们有一个在终端上运行的 shell，比如说 /dev/pts/1。 shell 已经在运行，我们无法重新启动它。
现在我们要编写一个C程序来“控制”shell，即它本身向用户提供一个类似shell的界面，读取用户的输入，将其传递到/dev/pts/1上的真实shell，有它执行它，读取 shell 的输出并将其打印回用户。
我知道如何完成此任务的一半：我知道如何收集用户的输入并将此输入注入到“真实 shell”：
#include <fcntl.h>
#include <sys/ioctl.h>
#include <stdio.h>
#define SIZE 100
int main(int argc, char** argv)
{
if( argc>1 )
{
int tty = open( argv[1], O_WRONLY|O_NONBLOCK);
if( tty!=-1 )
{
char *buf,buffer[SIZE+1];
while(1)
{
printf("> ");
fgets( buffer, SIZE, stdin );
if( buffer[0]=='q' && buffer[1]=='u' && buffer[2]=='i' && buffer[3]=='t' ) break;
for(buf=buffer; *buf!='\0'; buf++ ) ioctl(tty, TIOCSTI, buf);
}
close(tty);
}
else printf("Failed to open terminal %s\n", argv[1]);
}
return 0;
}
上面的内容会将您的输入传递到在终端中运行的 shell（在第一个参数中给出其名称）并且让 shell 执行它。但是，我现在不知道如何读取 shell 的输出。
有什么建议吗？
Suppose we have a shell running on terminal, let's say, /dev/pts/1. The shell is already running and we can't restart it.
Now we want to write a C program that will 'control' the shell, i.e. which will itself provide a shell-like interface to the user, read user's input, pass it on to the real shell on /dev/pts/1, have it execute it, read shell's output and print it back to the user.
I know how to do half of this task: I know how to gather user's input and inject this input to the 'real shell' :
#include <fcntl.h>
#include <sys/ioctl.h>
#include <stdio.h>
#define SIZE 100
int main(int argc, char** argv)
{
if( argc>1 )
{
int tty = open( argv[1], O_WRONLY|O_NONBLOCK);
if( tty!=-1 )
{
char *buf,buffer[SIZE+1];
while(1)
{
printf("> ");
fgets( buffer, SIZE, stdin );
if( buffer[0]=='q' && buffer[1]=='u' && buffer[2]=='i' && buffer[3]=='t' ) break;
for(buf=buffer; *buf!='\0'; buf++ ) ioctl(tty, TIOCSTI, buf);
}
close(tty);
}
else printf("Failed to open terminal %s\n", argv[1]);
}
return 0;
}
The above will pass on your input to shell running in terminal ( give its name in the first argument ) and have the shell execute it. However, I don't know how to read the shell's output now.
Any tips?
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您可以使用 管道 来实现这一点。 Linux shell 允许重定向。
我用管道来控制tty。
You can use pipes for that. Linux shells allow redirection.
I used pipes to control tty's.
有些程序允许您更改进程的控制终端：reptyr和 injcode 就是两个这样的程序。
然而，我确实相信他们会切断另一个终端，所以根据您的需要，这可能完全适合也可能不完全适合。
There are programs that allow you to change the controlling terminal for a process: reptyr and injcode are two such programs.
I do believe that they sever the other terminal, however, so depending on your needs this may or may not fit exactly.
请查看 libpipeline。也许这会帮助你......
please take a look at libpipeline. maybe this will help you...