Python错误：找不到命令

Question

我最近买了一本书开始玩一些 python，其中一个脚本如下：

#!/usr/bin/python2.7
import sys
import socket
import getopt
import threading
import subprocess


# define some global variables
listen             = False
command            = False
upload             = False
execute            = ""
target             = ""
upload_destination = ""
port               = 0

# this runs a command and returns the output
def run_command(command):

    # trim the newline
    command = command.rstrip()

    # run the command and get the output back
    try:
        output = subprocess.check_output(command,stderr=subprocess.STDOUT, shell=True)
    except:
        output = "Failed to execute command.\r\n"

    # send the output back to the client
    return output

# this handles incoming client connections
def client_handler(client_socket):
    global upload
    global execute
    global command

    # check for upload
    if len(upload_destination):

        # read in all of the bytes and write to our destination
        file_buffer = ""

        # keep reading data until none is available
        while True:
            data = client_socket.recv(1024)

            if not data:
                break
            else:
                file_buffer += data

        # now we take these bytes and try to write them out
        try:
            file_descriptor = open(upload_destination,"wb")
            file_descriptor.write(file_buffer)
            file_descriptor.close()

            # acknowledge that we wrote the file out
            client_socket.send("Successfully saved file to %s\r\n" % upload_destination)
        except:
            client_socket.send("Failed to save file to %s\r\n" % upload_destination)



    # check for command execution
    if len(execute):

        # run the command
        output = run_command(execute)

        client_socket.send(output)


    # now we go into another loop if a command shell was requested
    if command:

        while True:
            # show a simple prompt
            client_socket.send("<BHP:#> ")

            # now we receive until we see a linefeed (enter key)
            cmd_buffer = ""
            while "\n" not in cmd_buffer:
                cmd_buffer += client_socket.recv(1024)


            # we have a valid command so execute it and send back the results
            response = run_command(cmd_buffer)

            # send back the response
            client_socket.send(response)

# this is for incoming connections
def server_loop():
    global target
    global port

    # if no target is defined we listen on all interfaces
    if not len(target):
        target = "0.0.0.0"

    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server.bind((target,port))

    server.listen(5)        

    while True:
        client_socket, addr = server.accept()

        # spin off a thread to handle our new client
        client_thread = threading.Thread(target=client_handler,args=(client_socket,))
        client_thread.start()


# if we don't listen we are a client....make it so.
def client_sender(buffer):

    client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    try:
        # connect to our target host
        client.connect((target,port))

        # if we detect input from stdin send it 
        # if not we are going to wait for the user to punch some in

        if len(buffer):

            client.send(buffer)

        while True:

            # now wait for data back
            recv_len = 1
            response = ""

            while recv_len:
                data     = client.recv(4096)
                recv_len = len(data)
                response+= data

                if recv_len < 4096:
                    break

            print response, 

            # wait for more input
            buffer = raw_input("")
            buffer += "\n"                        

            # send it off
            client.send(buffer)


    except:
        # just catch generic errors - you can do your homework to beef this up
        print "[*] Exception! Exiting."

        # teardown the connection                  
        client.close()  




def usage():
    print "Netcat Replacement"
    print
    print "Usage: bhpnet.py -t target_host -p port"
    print "-l --listen                - listen on [host]:[port] for incoming connections"
    print "-e --execute=file_to_run   - execute the given file upon receiving a connection"
    print "-c --command               - initialize a command shell"
    print "-u --upload=destination    - upon receiving connection upload a file and write to [destination]"
    print
    print
    print "Examples: "
    print "bhpnet.py -t 192.168.0.1 -p 5555 -l -c"
    print "bhpnet.py -t 192.168.0.1 -p 5555 -l -u=c:\\target.exe"
    print "bhpnet.py -t 192.168.0.1 -p 5555 -l -e=\"cat /etc/passwd\""
    print "echo 'ABCDEFGHI' | ./bhpnet.py -t 192.168.11.12 -p 135"
    sys.exit(0)


def main():
    global listen
    global port
    global execute
    global command
    global upload_destination
    global target

    if not len(sys.argv[1:]):
        usage()

    # read the commandline options
    try:
        opts, args = getopt.getopt(sys.argv[1:],"hle:t:p:cu:",["help","listen","execute","target","port","command","upload"])
    except getopt.GetoptError as err:
        print str(err)
        usage()


    for o,a in opts:
        if o in ("-h","--help"):
            usage()
        elif o in ("-l","--listen"):
            listen = True
        elif o in ("-e", "--execute"):
            execute = a
        elif o in ("-c", "--commandshell"):
            command = True
        elif o in ("-u", "--upload"):
            upload_destination = a
        elif o in ("-t", "--target"):
            target = a
        elif o in ("-p", "--port"):
            port = int(a)
        else:
            assert False,"Unhandled Option"


    # are we going to listen or just send data from stdin
    if not listen and len(target) and port > 0:

        # read in the buffer from the commandline
        # this will block, so send CTRL-D if not sending input
        # to stdin
        buffer = sys.stdin.read()

        # send data off
        client_sender(buffer)   

    # we are going to listen and potentially 
    # upload things, execute commands and drop a shell back
    # depending on our command line options above
    if listen:
        server_loop()

main() 

我已经调试了脚本并尝试在终端中运行它，但它看起来像挂了一段时间，然后我收到以下错误：

./bhnet.py: line 10: listen: command not found
./bhnet.py: line 11: =: command not found
./bhnet.py: line 12: upload: command not found
./bhnet.py: line 13: execute: command not found
./bhnet.py: line 14: target: command not found
./bhnet.py: line 15: upload_destination: command not found
./bhnet.py: line 16: port: command not found
./bhnet.py: line 19: syntax error near unexpected token `('
./bhnet.py: line 19: `def run_command(command):'

我用书中的代码检查了代码，甚至有实际的代码，所以我也尝试了，但仍然没有。我希望我能比这更具体。任何建议，将不胜感激。谢谢。

Answer 1

这不是我的专业知识，但我会试着解释一下。

背景信息

当您在类 Unix 系统中运行脚本时，通常您可以调用解释器程序，并将脚本的路径作为参数传递，例如python bhnet.py.

但是，如果您有适当的配置，您也可以将脚本作为独立的可执行文件运行：./bhnet.py。为此，您通常需要：

1. 确保已开启执行权限（chmod +x 或同等权限）。

2. 脚本的第一行以符号#!（称为“shebang”）开头，后跟要使用的解释器的路径。

您的情况

文件中的第一行是#!/usr/bin/python2.7，这似乎很合理。当你运行./bhnet.py 时应该发生的是/usr/bin/python2.7 的解释器应该习惯于运行你的脚本。只要/usr/bin/python2.7是Python解释器就可以了……

但是，似乎正在发生的事情是，当您运行 ./bhnet.py 时调用的任何解释器都试图将脚本作为 shell 脚本而不是 Python 运行。也许由于某种原因，路径/usr/bin/python2.7 上的任何东西都不是Python。或者您的文件实际上并非以您在问题中粘贴的内容开头，但您可能不小心用不同的解释器指令覆盖了文件中的第一行，例如#!/bin/sh？可能还有其他原因也可能导致这种情况。

无论如何，无论您的默认 python 是什么，似乎都可以正常工作。 （要查看默认指向的内容，您可以运行 which python。）

推荐

如果您想将文件作为独立的可执行文件运行（即./bhnet.py），请尝试将第一行更改为：

#!/usr/bin/env python

这似乎是recommended shebang line for Python，在您的情况下应该可以正常工作。但我仍然很想知道你的/usr/bin/python2.7 发生了什么。

Answer 2

如果文件是在 Windows 上创建的，请尝试在类似 UNIX 的系统上运行之前运行 dos2unix。