blocks|key|1762272|text|提前终止Python脚本的一种简单方法是使用内置的quit()函数。不需要导入任何库，而且高效且简单。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1762273|示例：|1762274|#do+stuff
if+this+==+that:
++quit()|code-block|syntax|javascript|1762275|entityMap^0|P|6|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

A simple way to terminate a Python script early is to use the built-in <code>quit()</code> function. There is no need to import any library, and it is efficient and simple.

Example:

<pre><code>#do stuff
if this == that:
 quit()
</code></pre>

blocks|key|1547191|text|另一种方式是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1547192|raise+SystemExit|code-block|syntax|javascript|1547193|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Another way is:

<pre><code>raise SystemExit
</code></pre>

blocks|key|1762236|text|虽然您通常应该更喜欢sys.exit，因为它比其他代码更“友好”，但它实际上所做的只是引发一个异常。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1762237|如果您确定需要立即退出进程，并且您可能处于某个异常处理程序的内部，则可以使用另一个函数os._exit，该函数在C级别立即终止，并且不会执行任何正常的解释器拆卸操作；例如，不会执行用"atexit“模块注册的钩子。|1762238|entityMap^0|A|8|0|17|8|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

While you should generally prefer <code>sys.exit</code> because it is more "friendly" to other code, all it actually does is raise an exception.

If you are sure that you need to exit a process immediately, and you might be inside of some exception handler which would catch <code>SystemExit</code>, there is another function - <code>os._exit</code> - which terminates immediately at the C level and does not perform any of the normal tear-down of the interpreter; for example, hooks registered with the "atexit" module are not executed.

blocks|key|1547461|text|我刚刚发现，在编写多线程应用程序时，raise+SystemExit和sys.exit()都只会杀死正在运行的线程。另一方面，os._exit()退出整个过程。这在"Why+does+sys.exit()+not+exit+when+called+inside+a+thread+in+Python?“中已经讨论过了。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1547462|下面的例子有两个线程。肯尼和卡特曼。卡特曼应该永远活着，但肯尼被递归调用，应该在3秒后死亡。(递归调用不是最好的方法，但我还有其他原因)|1547463|如果我们也想让卡特曼死在肯尼死的时候，肯尼应该和os._exit一起离开，否则，只有肯尼会死，卡特曼会永远活着。|1547464|import+threading
import+time
import+sys
import+os

def+kenny(num=0):
++++if+num+>+3:
++++++++#+print("Kenny+dies+now...")
++++++++#+raise+SystemExit+#Kenny+will+die,+but+Cartman+will+live+forever
++++++++#+sys.exit(1)+#Same+as+above

++++++++print("Kenny+dies+and+also+kills+Cartman!")
++++++++os._exit(1)
++++while+True:
++++++++print("Kenny+lives:+{0}".format(num))
++++++++time.sleep(1)
++++++++num+%2B=+1
++++++++kenny(num)

def+cartman():
++++i+=+0
++++while+True:
++++++++print("Cartman+lives:+{0}".format(i))
++++++++i+%2B=+1
++++++++time.sleep(1)

if+__name__+==+'__main__':
++++daemon_kenny+=+threading.Thread(name='kenny',+target=kenny)
++++daemon_cartman+=+threading.Thread(name='cartman',+target=cartman)
++++daemon_kenny.setDaemon(True)
++++daemon_cartman.setDaemon(True)

++++daemon_kenny.start()
++++daemon_cartman.start()
++++daemon_kenny.join()
++++daemon_cartman.join()|code-block|syntax|javascript|1547465|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/905189/why-does-sys-exit-not-exit-when-called-inside-a-thread-in-python/5120178#5120178^0|I|G|Z|A|1R|A|2B|1V|0|0|0|O|8|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]]|E|$]]|$1|F|3|G|5|6|7|16|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1A|8|@]|D|@]|E|$M|N]]|$1|O|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

I've just found out that when writing a multithreadded app, <code>raise SystemExit</code> and <code>sys.exit()</code> both kills only the running thread. On the other hand, <code>os._exit()</code> exits the whole process. This was discussed in "<a href="https://stackoverflow.com/questions/905189/why-does-sys-exit-not-exit-when-called-inside-a-thread-in-python/5120178#5120178">Why does sys.exit() not exit when called inside a thread in Python?</a>".

The example below has 2 threads. Kenny and Cartman. Cartman is supposed to live forever, but Kenny is called recursively and should die after 3 seconds. (recursive calling is not the best way, but I had other reasons)

If we also want Cartman to die when Kenny dies, Kenny should go away with <code>os._exit</code>, otherwise, only Kenny will die and Cartman will live forever.

<pre><code>import threading
import time
import sys
import os

def kenny(num=0):
 if num &gt; 3:
 # print("Kenny dies now...")
 # raise SystemExit #Kenny will die, but Cartman will live forever
 # sys.exit(1) #Same as above

 print("Kenny dies and also kills Cartman!")
 os._exit(1)
 while True:
 print("Kenny lives: {0}".format(num))
 time.sleep(1)
 num += 1
 kenny(num)

def cartman():
 i = 0
 while True:
 print("Cartman lives: {0}".format(i))
 i += 1
 time.sleep(1)

if __name__ == '__main__':
 daemon_kenny = threading.Thread(name='kenny', target=kenny)
 daemon_cartman = threading.Thread(name='cartman', target=cartman)
 daemon_kenny.setDaemon(True)
 daemon_cartman.setDaemon(True)

 daemon_kenny.start()
 daemon_cartman.start()
 daemon_kenny.join()
 daemon_cartman.join()
</code></pre>

blocks|key|1547246|text|from+sys+import+exit
exit()|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1547247|作为参数，您可以传递一个退出代码，该代码将返回给OS。默认值为0。|unstyled|1547248|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>from sys import exit
exit()
</code></pre>

As a parameter you can pass an exit code, which will be returned to OS. Default is 0.

blocks|key|1762403|text|在Python3.5中，我尝试在不使用模块(例如sys、Biopy)的情况下合并类似的代码，而不是使用内置的模块来停止脚本并向用户打印错误消息。下面是我的例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1762404|##+My+example:
if+"ATG"+in+my_DNA:+
++++##+<Do+something+&+proceed...>
else:+
++++print("Start+codon+is+missing!+Check+your+DNA+sequence!")
++++exit()+##+as+most+folks+said+above|code-block|syntax|javascript|1762405|后来，我发现抛出一个错误更简洁：|1762406|##+My+example+revised:
if+"ATG"+in+my_DNA:+
++++##+<Do+something+&+proceed...>
else:+
++++raise+ValueError("Start+codon+is+missing!+Check+your+DNA+sequence!")|1762407|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

In Python 3.5, I tried to incorporate similar code without use of modules (e.g. sys, Biopy) other than what's built-in to stop the script and print an error message to my users. Here's my example:

<pre><code>## My example:
if "ATG" in my_DNA: 
 ## &lt;Do something &amp; proceed...&gt;
else: 
 print("Start codon is missing! Check your DNA sequence!")
 exit() ## as most folks said above
</code></pre>

Later on, I found it is more succinct to just throw an error:

<pre><code>## My example revised:
if "ATG" in my_DNA: 
 ## &lt;Do something &amp; proceed...&gt;
else: 
 raise ValueError("Start codon is missing! Check your DNA sequence!")
</code></pre>

blocks|key|1762487|text|我的两点意见。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1762488|Python+3.8.1，Windows+10，64位。|1762489|sys.exit()不能直接为我工作。|offset|length|style|CODE|1762490|我有几个相邻的循环。|1762491|首先，我声明了一个布尔变量，我称之为immediateExit。|1762492|因此，在程序代码的开头，我写道：|1762493|immediateExit+=+False|code-block|syntax|javascript|1762494|然后，从最内部(嵌套)的循环异常开始，我写道：|1762495|++++++++++++immediateExit+=+True
++++++++++++sys.exit('CSV+file+corrupted+0.')|1762496|然后我进入外部循环的直接延续，在代码执行其他任何东西之前，我写道：|1762497|++++if+immediateExit:
++++++++sys.exit('CSV+file+corrupted+1.')|1762498|根据复杂性的不同，有时还需要在except部分等中重复上面的语句。|1762499|++++if+immediateExit:
++++++++sys.exit('CSV+file+corrupted+1.5.')|1762500|自定义消息也用于我的个人调试，因为数字也是出于相同的目的-查看脚本真正存在的位置。|1762501|'CSV+file+corrupted+1.5.'|1762502|在我的特殊情况下，我正在处理CSV文件，如果软件检测到它已损坏，我不希望软件接触它。因此，对我来说，在检测到可能的损坏后立即退出整个Python脚本是非常重要的。|1762503|随着系统逐渐退出所有循环，我设法做到了这一点。|1762504|完整代码：(需要进行一些更改，因为它是内部任务的专有代码)：|1762505|immediateExit+=+False
start_date+=+'1994.01.01'
end_date+=+'1994.01.04'
resumedDate+=+end_date


end_date_in_working_days+=+False
while+not+end_date_in_working_days:
++++try:
++++++++end_day_position+=+working_days.index(end_date)

++++++++end_date_in_working_days+=+True
++++except+ValueError:+#+try+statement+from+end_date+in+workdays+check
++++++++print(current_date_and_time())
++++++++end_date+=+input('>>+{}+is+not+in+the+list+of+working+days.+Change+the+date+(YYYY.MM.DD):+'.format(end_date))
++++++++print('New+end+date:+',+end_date,+'\n')
++++++++continue


++++csv_filename+=+'test.csv'
++++csv_headers+=+'date,rate,brand\n'+#+not+real+headers,+this+is+just+for+example
++++try:
++++++++with+open(csv_filename,+'r')+as+file:
++++++++++++print('***\nOld+file+{}+found.+Resuming+the+file+by+re-processing+the+last+date+lines.\nThey+shall+be+deleted+and+re-processed.\n***\n'.format(csv_filename))
++++++++++++last_line+=+file.readlines()[-1]
++++++++++++start_date+=+last_line.split(',')[0]+#+assigning+the+start+date+to+be+the+last+like+date.
++++++++++++resumedDate+=+start_date

++++++++++++if+last_line+==+csv_headers:
++++++++++++++++pass
++++++++++++elif+start_date+not+in+working_days:
++++++++++++++++print('***\n\n{}+file+might+be+corrupted.+Erase+or+edit+the+file+to+continue.\n***'.format(csv_filename))
++++++++++++++++immediateExit+=+True
++++++++++++++++sys.exit('CSV+file+corrupted+0.')
++++++++++++else:
++++++++++++++++start_date+=+last_line.split(',')[0]+#+assigning+the+start+date+to+be+the+last+like+date.
++++++++++++++++print('\nLast+date:',+start_date)
++++++++++++++++file.seek(0)+#+setting+the+cursor+at+the+beginnning+of+the+file
++++++++++++++++lines+=+file.readlines()+#+reading+the+file+contents+into+a+list
++++++++++++++++count+=+0+#+nr.+of+lines+with+last+date
++++++++++++++++for+line+in+lines:+#cycling+through+the+lines+of+the+file
++++++++++++++++++++if+line.split(',')[0]+==+start_date:+#+cycle+for+counting+the+lines+with+last+date+in+it.
++++++++++++++++++++++++count+=+count+%2B+1
++++++++if+immediateExit:
++++++++++++sys.exit('CSV+file+corrupted+1.')
++++++++for+iter+in+range(count):+#+removing+the+lines+with+last+date
++++++++++++lines.pop()
++++++++print('\n{}+lines+removed+from+date:+{}+in+{}+file'.format(count,+start_date,+csv_filename))



++++++++if+immediateExit:
++++++++++++sys.exit('CSV+file+corrupted+1.2.')
++++++++with+open(csv_filename,+'w')+as+file:
++++++++++++print('\nFile',+csv_filename,+'open+for+writing')
++++++++++++file.writelines(lines)

++++++++++++print('\nRemoving',+count,+'lines+from',+csv_filename)

++++++++fileExists+=+True

++++except:
++++++++if+immediateExit:
++++++++++++sys.exit('CSV+file+corrupted+1.5.')
++++++++with+open(csv_filename,+'w')+as+file:
++++++++++++file.write(csv_headers)
++++++++++++fileExists+=+False
++++if+immediateExit:
++++++++sys.exit('CSV+file+corrupted+2.')|1762506|entityMap^0|0|0|0|A|0|0|I|D|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1L|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1M|8|@$F|1N|G|1O|H|I]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1P|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1Q|8|@$F|1R|G|1S|H|I]]|9|@]|A|$]]|$1|N|3|O|5|6|7|1T|8|@]|9|@]|A|$]]|$1|P|3|Q|5|R|7|1U|8|@]|9|@]|A|$S|T]]|$1|U|3|V|5|6|7|1V|8|@]|9|@]|A|$]]|$1|W|3|X|5|R|7|1W|8|@]|9|@]|A|$S|T]]|$1|Y|3|Z|5|6|7|1X|8|@]|9|@]|A|$]]|$1|10|3|11|5|R|7|1Y|8|@]|9|@]|A|$S|T]]|$1|12|3|13|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|14|3|15|5|R|7|20|8|@]|9|@]|A|$S|T]]|$1|16|3|17|5|6|7|21|8|@]|9|@]|A|$]]|$1|18|3|19|5|R|7|22|8|@]|9|@]|A|$S|T]]|$1|1A|3|1B|5|6|7|23|8|@]|9|@]|A|$]]|$1|1C|3|1D|5|6|7|24|8|@]|9|@]|A|$]]|$1|1E|3|1F|5|6|7|25|8|@]|9|@]|A|$]]|$1|1G|3|1H|5|R|7|26|8|@]|9|@]|A|$S|T]]|$1|1I|3|-4|5|6|7|27|8|@]|9|@]|A|$]]]|1J|$]]

My two cents.

Python 3.8.1, Windows 10, 64-bit.

<code>sys.exit()</code> does not work directly for me.

I have several nexted loops.

First I declare a boolean variable, which I call <code>immediateExit</code>.

So, in the beginning of the program code I write:

<pre><code>immediateExit = False
</code></pre>

Then, starting from the most inner (nested) loop exception, I write:

<pre><code> immediateExit = True
 sys.exit('CSV file corrupted 0.')
</code></pre>

Then I go into the immediate continuation of the outer loop, and before anything else being executed by the code, I write:

<pre><code> if immediateExit:
 sys.exit('CSV file corrupted 1.')
</code></pre>

Depending on the complexity, sometimes the above statement needs to be repeated also in except sections, etc.

<pre><code> if immediateExit:
 sys.exit('CSV file corrupted 1.5.')
</code></pre>

The custom message is for my personal debugging, as well, as the numbers are for the same purpose - to see where the script really exits. 

<pre><code>'CSV file corrupted 1.5.'
</code></pre>

In my particular case I am processing a CSV file, which I do not want the software to touch, if the software detects it is corrupted. Therefore for me it is very important to exit the whole Python script immediately after detecting the possible corruption.

And following the gradual sys.exit-ing from all the loops I manage to do it.

Full code: (some changes were needed because it is proprietory code for internal tasks):

<pre><code>immediateExit = False
start_date = '1994.01.01'
end_date = '1994.01.04'
resumedDate = end_date


end_date_in_working_days = False
while not end_date_in_working_days:
 try:
 end_day_position = working_days.index(end_date)

 end_date_in_working_days = True
 except ValueError: # try statement from end_date in workdays check
 print(current_date_and_time())
 end_date = input('&gt;&gt; {} is not in the list of working days. Change the date (YYYY.MM.DD): '.format(end_date))
 print('New end date: ', end_date, '\n')
 continue


 csv_filename = 'test.csv'
 csv_headers = 'date,rate,brand\n' # not real headers, this is just for example
 try:
 with open(csv_filename, 'r') as file:
 print('***\nOld file {} found. Resuming the file by re-processing the last date lines.\nThey shall be deleted and re-processed.\n***\n'.format(csv_filename))
 last_line = file.readlines()[-1]
 start_date = last_line.split(',')[0] # assigning the start date to be the last like date.
 resumedDate = start_date

 if last_line == csv_headers:
 pass
 elif start_date not in working_days:
 print('***\n\n{} file might be corrupted. Erase or edit the file to continue.\n***'.format(csv_filename))
 immediateExit = True
 sys.exit('CSV file corrupted 0.')
 else:
 start_date = last_line.split(',')[0] # assigning the start date to be the last like date.
 print('\nLast date:', start_date)
 file.seek(0) # setting the cursor at the beginnning of the file
 lines = file.readlines() # reading the file contents into a list
 count = 0 # nr. of lines with last date
 for line in lines: #cycling through the lines of the file
 if line.split(',')[0] == start_date: # cycle for counting the lines with last date in it.
 count = count + 1
 if immediateExit:
 sys.exit('CSV file corrupted 1.')
 for iter in range(count): # removing the lines with last date
 lines.pop()
 print('\n{} lines removed from date: {} in {} file'.format(count, start_date, csv_filename))



 if immediateExit:
 sys.exit('CSV file corrupted 1.2.')
 with open(csv_filename, 'w') as file:
 print('\nFile', csv_filename, 'open for writing')
 file.writelines(lines)

 print('\nRemoving', count, 'lines from', csv_filename)

 fileExists = True

 except:
 if immediateExit:
 sys.exit('CSV file corrupted 1.5.')
 with open(csv_filename, 'w') as file:
 file.write(csv_headers)
 fileExists = False
 if immediateExit:
 sys.exit('CSV file corrupted 2.')

</code></pre>

blocks|key|1547645|text|只需将quit()放在代码的末尾，就可以结束python脚本。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1547646|entityMap^0|3|6|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

Just put at the end of your code <code>quit()</code> and that should close a python script.

I am aware of the <code>die()</code> command in PHP which exits a script early.

How can I do this in Python?

How to terminate a script?

我知道PHP中的die()命令可以提前退出脚本。我如何在Python中做到这一点？

问如何终止脚本？
EN

回答 8

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