c – 子进程的异步双向IO重定向

我试图找出子进程的异步双向IO重定向的通用方法.基本上,我想生成一个等待输入的交互式子进程,应该回读任何输出.我尝试通过生成一个新的 python进程来试验 python.subprocess.试图实现的基本简化示例如下

process = subprocess.Popen(['/usr/bin/python'],shell=False,stdin=subprocess.PIPE,stdout=subprocess.PIPE)
while True:
    output = process.stdout.readline()
    print output
    input = sys.stdin.readline()
    process.stdin.write(input)

执行上面的代码片段只是挂起而没有任何输出.我尝试使用/usr/bash和/usr/bin/irb运行,但结果完全相同.我的猜测是,缓冲的IO根本不适合IO重定向.

所以我的问题是,在不刷新缓冲区或退出子进程的情况下读取子进程的输出是否可行？

following post提到了IPC插座,但为此我必须改变儿童过程,这可能是不可行的.有没有其他方法可以实现它？

注意***我的最终目标是创建一个可以与远程Web客户端交互的服务器REPL过程.虽然给出的示例是Python,但我的最终目标是通过通用包装器包装所有可用的REPL.

在答案的一些建议的帮助下,我想出了以下内容

#!/usr/bin/python
import subprocess,os,select
proc = subprocess.Popen(['/usr/bin/python'],stdout=subprocess.PIPE,stderr=subprocess.PIPE)
for i in xrange(0,5):
    inputready,outputready,exceptready = select.select([proc.stdout,proc.stderr],[proc.stdout,0)
    if not inputready: print "No Data",print inputready,exceptready
    for s in inputready: print s.fileno(),s.readline()
proc.terminate()
print "After Terminating"
for i in xrange(0,s.readline()

现在,虽然程序没有陷入僵局,但不幸的是没有输出.运行上面的代码我得到了

No Data [] [] []
No Data [] [] []
No Data [] [] []
No Data [] [] []
No Data [] [] []
After Terminating
No Data [] [] []
No Data [] [] []
No Data [] [] []
No Data [] [] []
No Data [] [] []

仅供参考,
像运行python一样

/usr/bin/python 2>&1|tee test.out

似乎工作得很好.

我还想出了一个’C’代码.但结果并没有什么不同.

int kbhit() {
    struct timeval tv;
    fd_set fds;
    tv.tv_sec = tv.tv_usec = 0;
    FD_ZERO(&fds);
    FD_SET(STDIN_FILENO,&fds);
    select(STDIN_FILENO+1,&fds,NULL,&tv);
    return FD_ISSET(STDIN_FILENO,&fds);
}
void receive(char *str) {
    char ch;
    fprintf(stderr,"IN1n");
    if(!kbhit()) return;
    fprintf(stderr,"IN2n");
    fprintf(stderr,"%dn",kbhit());
    for(;kbhit() && (ch=fgetc(stdin))!=EOF;) {
        fprintf(stderr,"%c,%d",ch,kbhit());
    }
    fprintf(stderr,"Donen");
}
int main(){
    pid_t pid;
    int rv,pipeP2C[2],pipeC2P[2];  
    pipe(pipeP2C);
    pipe(pipeC2P);
    pid=fork();
    if(pid){
        dup2(pipeP2C[1],1); /* Replace stdout with out side of the pipe */
        close(pipeP2C[0]);  /* Close unused side of pipe (in side) */
        dup2(pipeC2P[0],0); /* Replace stdin with in side of the pipe */
        close(pipeC2P[1]);  /* Close unused side of pipe (out side) */
        setvbuf(stdout,(char*)NULL,_IONBF,0);   /* Set non-buffered output on stdout */
        sleep(2);
        receive("quit()n");
        wait(&rv);              /* Wait for child process to end */
        fprintf(stderr,"Child exited with a %d valuen",rv);
    }
    else{
        dup2(pipeP2C[0],0); /* Replace stdin with the in side of the pipe */
        close(pipeP2C[1]);  /* Close unused side of pipe (out side) */
        dup2(pipeC2P[1],1); /* Replace stdout with the out side of the pipe */
        close(pipeC2P[0]);  /* Close unused side of pipe (out side) */
        setvbuf(stdout,0);   /* Set non-buffered output on stdout */
        close(2),dup2(1,2); /*Redirect stderr to stdout */
        if(execl("/usr/bin/python","/usr/bin/python",NULL) == -1){
            fprintf(stderr,"execl Error!");
            exit(1);
        }
    }
    return 0;
}

inputready,exceptready = select.select(
    [proc.stdout,# read list
    [proc.stdout,# write list
    [proc.stdout,# error list.
    0)                          # time out.

#!/usr/bin/python
import subprocess,select,time

path = "/usr/bin/python"
proc = subprocess.Popen([path,"foo.py"],5):
    time.sleep(1)
    inputready,exceptready = select.select(
        [proc.stdout,[proc.stdin,],proc.stderr,proc.stdin],0)
    if not inputready:
        print "No Data",exceptready
    for s in inputready:
        print s.fileno(),s.readline()

proc.terminate()
print "After Terminating"

for i in xrange(0,s.readline()

#!/usr/bin/python
print "Hello,world!"

#!/usr/bin/python
import subprocess,0)
    for s in inputready:
        line = s.readline()
        if line:
            print s.fileno(),line

proc.terminate()
print "After Terminating"

for i in xrange(0,line

/usr/bin/python </dev/null 2>&1|tee test.out