如何在CTRL+;C在python中被按下
我是python新手,我遇到了以下问题。 我有一个脚本,可以逐个处理文件,并根据输入文件名将输出写入单独的文件。有时我需要中断脚本,但我希望让它完成当前文件的处理,然后终止(以避免结果文件信息不完整)。如何在python中编写这种行为 这是我试过的 a) 试除块如何在CTRL+;C在python中被按下,python,loops,Python,Loops,我是python新手,我遇到了以下问题。 我有一个脚本,可以逐个处理文件,并根据输入文件名将输出写入单独的文件。有时我需要中断脚本,但我希望让它完成当前文件的处理,然后终止(以避免结果文件信息不完整)。如何在python中编写这种行为 这是我试过的 a) 试除块 x = 1 print "Script started." while True: try: print "Processing file #",x,"started...&quo
x = 1
print "Script started."
while True:
try:
print "Processing file #",x,"started...",
# do something time-cosnuming
time.sleep(1)
x += 1
print " finished."
except KeyboardInterrupt:
print "Bye"
print "x=",x
sys.exit()
sys.exit()
输出:
Script started.
Processing file # 1 started... finished.
Processing file # 2 started... finished.
Processing file # 3 started... Bye
x= 3
Script started.
Processing file # 1 started... finished.
Processing file # 2 started... finished.
Processing file # 3 started...
Exiting by CTRL+C.
迭代#3没有优雅地完成
b) 系统异常钩子
OriginalExceptHook = sys.excepthook
def NewExceptHook(type, value, traceback):
global Terminator
Terminator = True
if type == KeyboardInterrupt:
#exit("\nExiting by CTRL+C.") # this line was here originally
print("\n\nExiting by CTRL+C.\n\n")
else:
OriginalExceptHook(type, value, traceback)
sys.excepthook = NewExceptHook
global Terminator
Terminator = False
x = 1
while True:
print "Processing file #",x,"started...",
# do something time-cosnuming
time.sleep(1)
x += 1
print " finished."
if Terminator:
print "I'll be back!"
break
print "Bye"
print "x=",x
sys.exit()
输出:
Script started.
Processing file # 1 started... finished.
Processing file # 2 started... finished.
Processing file # 3 started... Bye
x= 3
Script started.
Processing file # 1 started... finished.
Processing file # 2 started... finished.
Processing file # 3 started...
Exiting by CTRL+C.
迭代#3没有优雅地完成
UPD#1
@mguijarr,我稍微修改了代码如下:
import time, sys
x = 1
print "Script started."
stored_exception=None
while True:
try:
print "Processing file #",x,"started...",
# do something time-cosnuming
time.sleep(1)
print "Processing file #",x,"part two...",
time.sleep(1)
print " finished."
if stored_exception:
break
x += 1
except KeyboardInterrupt:
print "[CTRL+C detected]",
stored_exception=sys.exc_info()
print "Bye"
print "x=",x
if stored_exception:
raise stored_exception[0], stored_exception[1], stored_exception[2]
sys.exit()
输出是(在Win7-64位上使用“Python 2.7.6::Anaconda 2.0.0(64位)”进行测试):
输出为:
Script started.
Processing file # 1 1001 started...
Processing file # 1 1004 part two...
finished. 1 1006
Processing file # 2 2001 started...
Processing file # 2 2004 part two...
[CTRL+C detected] Processing file # 2 2001 started...
Processing file # 2 2004 part two...
finished. 2 2006
Bye
x= 2
y= 2007
Traceback (most recent call last):
File "test2.py", line 20, in <module>
time.sleep(1)
KeyboardInterrupt
脚本已启动。
已开始处理文件#1 1001。。。
正在处理文件#1 1004第二部分。。。
完成了。1 1006
正在处理文件#2 2001已开始。。。
正在处理文件#2 2004第二部分。。。
[CTRL+C检测到]已开始处理文件#2 2001。。。
正在处理文件#2 2004第二部分。。。
完成了。2 2006
拜伊
x=2
y=2007
回溯(最近一次呼叫最后一次):
文件“test2.py”,第20行,在
时间。睡眠(1)
键盘中断
我只需要使用一个异常处理程序,它将捕获键盘中断
和
存储异常。然后,在迭代完成时,如果出现异常
正在挂起,我将中断循环并重新引发异常(以允许正常异常
处理发生的机会)
这是可行的(使用Python 2.7进行了测试):
编辑:正如在评论中所发现的,这个答案对于原始海报来说并不令人满意,下面是一个基于线程的解决方案:
import time
import sys
import threading
print "Script started."
class MyProcessingThread(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
def run(self):
print "Processing file #",x,"started...",
# do something time-cosnuming
time.sleep(1)
print " finished."
for x in range(1,4):
task = MyProcessingThread()
task.start()
try:
task.join()
except KeyboardInterrupt:
break
print "Bye"
print "x=",x
sys.exit()
您可以编写一个信号处理函数
import signal,sys,time
terminate = False
def signal_handling(signum,frame):
global terminate
terminate = True
signal.signal(signal.SIGINT,signal_handling)
x=1
while True:
print "Processing file #",x,"started..."
time.sleep(1)
x+=1
if terminate:
print "I'll be back"
break
print "bye"
print x
按Ctrl+c发送一个SIGINT中断,该中断将输出:
Processing file # 1 started...
Processing file # 2 started...
^CI'll be back
bye
3
我觉得创建一个具有处理用户异常的状态的类要优雅一些,因为我不必处理不能跨不同模块工作的全局变量
import signal
import time
class GracefulExiter():
def __init__(self):
self.state = False
signal.signal(signal.SIGINT, self.change_state)
def change_state(self, signum, frame):
print("exit flag set to True (repeat to exit now)")
signal.signal(signal.SIGINT, signal.SIG_DFL)
self.state = True
def exit(self):
return self.state
x = 1
flag = GracefulExiter()
while True:
print("Processing file #",x,"started...")
time.sleep(1)
x+=1
print(" finished.")
if flag.exit():
break
这段代码看起来还可以,但行为异常。请参阅问题的更新。是否确实已重新启动?我认为异常只是搞乱了stdout,因为它被缓冲了(删除print语句末尾的“,”看起来确实如此。请参阅问题中的更新代码。我也不明白为什么会这样。请注意,在
x
递增之前按Ctrl-C,然后启动另一个循环,然后测试存储的异常和中断。还请注意,如果异常中断代码,则不能简单地继续前面的计算。您希望延迟中断,因此使用信号之类的东西似乎是唯一的方法。如果您不想得到不完整的结果,而不是等待结果,那么在Ctrl-C上丢弃当前文件也更自然。在这种情况下,你不需要任何特别的东西。捕获键盘中断后,只需清理当前文件。您的代码真的允许当前迭代优雅地完成吗?我也不能重现你的行为:我看不到在按下CTRL+C后打印的“再见”。只是例外信息。(我在win7-64位上使用“Python2.7.6::Anaconda 2.0.0(64位)”。@anandr,它是从我的终端复制的精确输出。我在linuxI上使用Python2.7.7,我不知道如何添加大代码块来评论,所以我更新了您的答案,以演示我在运行代码时看到的内容。这应该是公认的答案,它正是OP试图实现的。
import signal
import time
class GracefulExiter():
def __init__(self):
self.state = False
signal.signal(signal.SIGINT, self.change_state)
def change_state(self, signum, frame):
print("exit flag set to True (repeat to exit now)")
signal.signal(signal.SIGINT, signal.SIG_DFL)
self.state = True
def exit(self):
return self.state
x = 1
flag = GracefulExiter()
while True:
print("Processing file #",x,"started...")
time.sleep(1)
x+=1
print(" finished.")
if flag.exit():
break