Question

我有以下脚本（见下文），它采用stdin并操作一些简单的文件。

# Import Modules for script
import os, sys, fileinput, platform, subprocess

# Global variables
hostsFile = "hosts.txt"
hostsLookFile = "hosts.csv"

# Determine platform
plat = platform.system()

if plat == "Windows":

# Define Variables based on Windows and process
    currentDir = os.getcwd()
    hostsFileLoc = currentDir + "\\" + hostsFile
    hostsLookFileLoc = currentDir + "\\" + hostsLookFile
    ipAddress = sys.argv[1]
    hostName = sys.argv[2]
    hostPlatform = sys.argv[3]
    hostModel = sys.argv[4]

    # Add ipAddress to the hosts file for python to process 
    with open(hostsFileLoc,"a") as hostsFilePython:
        for line in open(hostsFilePython, "r"):
            if ipAddress in line:
                print "ipAddress \(" + ipAddress + "\) already present in hosts file"
            else:
                print "Adding ipAddress: " + ipAddress + " to file"
                hostsFilePython.write(ipAddress + "\n")

    # Add all details to the lookup file for displaying on-screen and added value
    with open(hostsLookFileLoc,"a") as hostsLookFileCSV:
        for line in open(hostsLookFileCSV, "r"):
            if ipAddress in line:
                print "ipAddress \(" + ipAddress + "\) already present in lookup file"
            else:
                print "Adding details: " + ipAddress + "," + hostName + "," + hostPlatform + "," + hostModel + " to file"
                hostsLookFileCSV.write(ipAddress + "," + hostName + "," + hostPlatform + "," + hostModel + "\n")

if plat == "Linux":

# Define Variables based on Linux and process
    currentDir = os.getcwd()
    hostsFileLoc = currentDir + "/" + hostsFile
    hostsLookFileLoc = currentDir + "/" + hostsLookFile
    ipAddress = sys.argv[1]
    hostName = sys.argv[2]
    hostPlatform = sys.argv[3]
    hostModel = sys.argv[4]

    # Add ipAddress to the hosts file for python to process 
    with open(hostsFileLoc,"a") as hostsFilePython:
        print "Adding ipAddress: " + ipAddress + " to file"
        hostsFilePython.write(ipAddress + "\n")

    # Add all details to the lookup file for displaying on-screen and added value
    with open(hostsLookFileLoc,"a") as hostsLookFileCSV:
        print "Adding details: " + ipAddress + "," + hostName + "," + hostPlatform + "," + hostModel + " to file"
        hostsLookFileCSV.write(ipAddress + "," + hostName + "," + hostPlatform + "," + hostModel + "\n")

此代码显然不起作用，因为for line in open(hostsFilePython, "r"):语法错误...我无法使用“open()”的当前文件对象。然而，这是我想要实现的，我该怎么做？

Answer 1

您想使用the a+ mode打开文件，以便您可以读取和写入，然后只使用现有的文件对象（hostsFilePython）。

但是，这仍然无效，因为您只能在文件耗尽前迭代一次。

值得注意的是，这不是很有效率。更好的计划是将数据读入集合，使用新值更新集合，然后将集合写入文件。（正如评论中所指出的，集合不会保留重复数据（对您的目的有用）和订单，这可能适用于您，也可能不适合您。如果没有，那么您可能需要使用列表，这样效率会降低）。

Answer 2

with open(hostsFileLoc) as hostsFilePython:
    lines = hostsFilePython.readlines()

for filename in lines:
    with open(hostsFileLoc, 'a') as hostFilePython:
        with open(filename) as hostsFile:
            for line in hostsFile.readlines():
                if ipAddress in line:
                   print "ipAddress \(" + ipAddress + "\) already present in hosts file"
                else:
                   print "Adding ipAddress: " + ipAddress + " to file"
                   hostsFilePython.write(ipAddress + "\n")

读取默认模式，因此您无需明确传递r。

相当于grep，但不使用open（）

2 个答案: