python - os.open（）：沒有這樣的設備或地址？

Question

我想嘗試一下我的手，命名管道，所以我下載了一段代碼，並修改它來測試：

fifoname = '/home/foo/pipefifo'      # must open same name 

def child(): 
    pipeout = os.open(fifoname, os.O_NONBLOCK|os.O_WRONLY) 
    # open fifo pipe file as fd 
    zzz = 0 
    while 1: 
     time.sleep(zzz) 
     os.write(pipeout, 'Spam %03d\n' % zzz) 
     zzz = (zzz+1) % 5 

def parent(): 
    pipein = open(fifoname, 'r')     # open fifo as stdio object 
    while 1: 
     line = pipein.readline()[:-1]   # blocks until data sent 
     print 'Parent %d got "%s" at %s' % (os.getpid(), line, time.time()) 

if __name__ == '__main__': 
    if not os.path.exists(fifoname): 
     os.mkfifo(fifoname)      # create a named pipe file 
    if len(sys.argv) == 1: 
     parent()         # run as parent if no args 
    else: 
      child() 

我試圖運行該腳本，它返回此錯誤：

pipeout = os.open(fifoname, os.O_NONBLOCK|os.O_WRONLY)  # open fifo pipe file as fd 
OSError: [Errno 6] No such device or address: '/home/carrier24sg/pipefifo' 

什麼導致了這個錯誤？ （我在Linux上運行的Python 2.6.5）

Answer 1

這是爲我工作在Linux上：

import time 
import os, sys 
fifoname = '/tmp/pipefifo' # must open same name 

def child(): 
    pipeout = os.open(fifoname, os.O_NONBLOCK|os.O_WRONLY)  # open fifo pipe file as fd 
    zzz = 0 
    while 1: 
     time.sleep(zzz) 
     os.write(pipeout, 'Spam %03d\n' % zzz) 
     zzz = (zzz+1) % 5 

def parent(): 
    pipein = open(fifoname, 'r') # open fifo as stdio object 
    while 1: 
    line = pipein.readline()[:-1] # blocks until data sent 
    print 'Parent %d got "%s" at %s' % (os.getpid(), line, time.time()) 

if __name__ == '__main__': 
    if not os.path.exists(fifoname): 
    os.mkfifo(fifoname)      # create a named pipe file 
    if len(sys.argv) == 1: 
     parent()         # run as parent if no args 
    else: 
     child() 

我認爲這個問題是與平臺相關的，在哪個平臺是嗎？ o也許有一些權限問題。

Answer 2

從man 7 fifo：

A process can open a FIFO in non-blocking mode. In this case, opening for read only will succeed even if no-one has opened on the write side yet, opening for write only will fail with ENXIO (no such device or address) unless the other end has already been opened.

所以你得到這個令人困惑的錯誤消息，因爲你試圖打開一個命名管道讀取着呢，你試圖打開它與非阻塞寫open(2)。

在您的具體示例中，如果在parent()之前運行child()，則會發生此錯誤。