我正在尝试使用 cmd 包在 Python 中创建一个 shell。我想重现“真实”shell（bash，csh，...）的行为，也就是说，当您键入命令并意识到自己在做什么是错误的时，您可以按 ctrl+c 来获取一个新的干净提示。
我试图捕捉 SIGINT，然后调用一个刚刚返回的方法，但它什么也没做。
这是一个示例示例：
#! /usr/bin/python
# -*- coding: utf-8 -*-
from cmd import Cmd
import signal
import sys
class myPrompt(Cmd):
def do_exit(self, inp):
"""
Exit the shell
"""
return True
def do_test(self):
print "hello"
return
p=myPrompt()
def signal_handler(sig, frame):
print "world"
p.do_test()
return
signal.signal(signal.SIGINT, signal_handler)
p.cmdloop()
编辑：
我按照 Peter Wood 的建议更改了我的代码：
#! /usr/bin/python
# -*- coding: utf-8 -*-
from cmd import Cmd
import signal
import sys
class myPrompt(Cmd):
def do_exit(self, inp):
"""
Exit the shell
"""
return True
def onecmd(self, line):
try:
return super().onecmd(line)
except:
return False
p=myPrompt()
p.cmdloop()
我收到此错误：
(Cmd) Traceback (most recent call last):
File "./test2.py", line 41, in <module>
p.cmdloop()
File "/usr/lib/python2.7/cmd.py", line 130, in cmdloop
line = raw_input(self.prompt)
KeyboardInterrupt
我已经写了一个你想要的工作版本。您应该覆盖类的cmdloop和onecmd方法Cmd。
我在cmdloop方法中为 KeyboardInterrupt 处理定义了一个新关键字：
if self.use_rawinput:
try:
line = input(self.prompt)
except EOFError:
line = "EOF"
except KeyboardInterrupt:
line = "ctrl_c" # You can handle the `KeyboardInterrupt` exception through this keyword.
我已经在onecmd方法中处理了这个关键字。如果line变量包含此关键字，则该方法将向\nSTDOUT写入 a并返回。
if line == "EOF":
self.lastcmd = ""
if line == "ctrl_c": # You can handle the `KeyboardInterrupt` exception in this `if` branch.
self.stdout.write("\n")
return
您可以在下面看到完整的代码工作代码：
#! /usr/bin/python
# -*- coding: utf-8 -*-
from cmd import Cmd
class MyPrompt(Cmd):
@staticmethod
def do_exit(*args):
return True
def cmdloop(self, intro=None):
"""Repeatedly issue a prompt, accept input, parse an initial prefix
off the received input, and dispatch to action methods, passing them
the remainder of the line as argument.
"""
self.preloop()
if self.use_rawinput and self.completekey:
try:
import readline
self.old_completer = readline.get_completer()
readline.set_completer(self.complete)
readline.parse_and_bind(self.completekey + ": complete")
except ImportError:
pass
try:
if intro is not None:
self.intro = intro
if self.intro:
self.stdout.write(str(self.intro) + "\n")
stop = None
while not stop:
if self.cmdqueue:
line = self.cmdqueue.pop(0)
else:
if self.use_rawinput:
try:
line = input(self.prompt)
except EOFError:
line = "EOF"
except KeyboardInterrupt:
line = "ctrl_c"
else:
self.stdout.write(self.prompt)
self.stdout.flush()
line = self.stdin.readline()
if not len(line):
line = "EOF"
else:
line = line.rstrip("\r\n")
line = self.precmd(line)
stop = self.onecmd(line)
stop = self.postcmd(stop, line)
self.postloop()
finally:
if self.use_rawinput and self.completekey:
try:
import readline
readline.set_completer(self.old_completer)
except ImportError:
pass
def onecmd(self, line):
"""Interpret the argument as though it had been typed in response
to the prompt.
This may be overridden, but should not normally need to be;
see the precmd() and postcmd() methods for useful execution hooks.
The return value is a flag indicating whether interpretation of
commands by the interpreter should stop.
"""
cmd, arg, line = self.parseline(line)
if not line:
return self.emptyline()
if cmd is None:
return self.default(line)
self.lastcmd = line
if line == "EOF":
self.lastcmd = ""
if line == "ctrl_c":
self.stdout.write("\n")
return
if cmd == "":
return self.default(line)
else:
try:
func = getattr(self, "do_" + cmd)
except AttributeError:
return self.default(line)
return func(arg)
p = MyPrompt()
p.cmdloop()
输出：
python3 test_cmd.py
(Cmd) test
*** Unknown syntax: test
(Cmd) test1
*** Unknown syntax: test1
(Cmd) test2 <-- Ctrl+C has been pushed and I got a new empty prompt
(Cmd) test3 <-- Ctrl+C has been pushed and I got a new empty prompt
(Cmd) <-- I got a new empty prompt
我希望我的解决方案可以帮助你。
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我来说两句