blocks|key|1408123|text|如果pid未运行，则向pid发送信号0将引发OSError异常，否则不执行任何操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1408124|import+os

def+check_pid(pid):++++++++
++++"""+Check+For+the+existence+of+a+unix+pid.+"""
++++try:
++++++++os.kill(pid,+0)
++++except+OSError:
++++++++return+False
++++else:
++++++++return+True|code-block|syntax|javascript|1408125|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|$]]

Sending signal 0 to a pid will raise an OSError exception if the pid is not running, and do nothing otherwise.

<pre><code>import os

def check_pid(pid): 
 """ Check For the existence of a unix pid. """
 try:
 os.kill(pid, 0)
 except OSError:
 return False
 else:
 return True
</code></pre>

blocks|key|1622915|text|在here中查找windows特有的获取运行进程及其ID的完整列表的方法。它应该是这样的|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1622916|from+win32com.client+import+GetObject
def+get_proclist():
++++WMI+=+GetObject('winmgmts:')
++++processes+=+WMI.InstancesOf('Win32_Process')
++++return+[process.Properties_('ProcessID').Value+for+process+in+processes]|code-block|syntax|javascript|1622917|然后，您可以根据此列表验证您获得的pid。我不知道性能成本，所以如果你要经常做pid验证，你最好检查一下。|1622918|对于*NIx，只需使用mluebke的解决方案。|1622919|entityMap|0|LINK|mutability|MUTABLE|url|http://mail.python.org/pipermail/python-win32/2003-December/001482.html^0|1|4|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Look <a href="http://mail.python.org/pipermail/python-win32/2003-December/001482.html" rel="noreferrer">here</a> for windows-specific way of getting full list of running processes with their IDs. It would be something like

<pre><code>from win32com.client import GetObject
def get_proclist():
 WMI = GetObject('winmgmts:')
 processes = WMI.InstancesOf('Win32_Process')
 return [process.Properties_('ProcessID').Value for process in processes]
</code></pre>

You can then verify pid you get against this list. I have no idea about performance cost, so you'd better check this if you're going to do pid verification often.

For *NIx, just use mluebke's solution.

blocks|key|1408242|text|我要说的是，无论您获取PID的目的是什么，都可以使用它，并优雅地处理错误。否则，这是一场经典的比赛(当你检查PID是否有效时，它可能是有效的，但稍后就会消失)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1408243|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I'd say use the PID for whatever purpose you're obtaining it and handle the errors gracefully. Otherwise, it's a classic race (the PID may be valid when you check it's valid, but go away an instant later)

blocks|key|1408278|text|mluebke代码不是100%25正确的；kill()还会引发EPERM+(拒绝访问)，在这种情况下，这显然意味着存在一个进程。这应该是可行的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1408279|(根据Jason+R.Coombs评论编辑)|1408280|import+errno
import+os

def+pid_exists(pid):
++++"""Check+whether+pid+exists+in+the+current+process+table.
++++UNIX+only.
++++"""
++++if+pid+<+0:
++++++++return+False
++++if+pid+==+0:
++++++++#+According+to+"man+2+kill"+PID+0+refers+to+every+process
++++++++#+in+the+process+group+of+the+calling+process.
++++++++#+On+certain+systems+0+is+a+valid+PID+but+we+have+no+way
++++++++#+to+know+that+in+a+portable+fashion.
++++++++raise+ValueError('invalid+PID+0')
++++try:
++++++++os.kill(pid,+0)
++++except+OSError+as+err:
++++++++if+err.errno+==+errno.ESRCH:
++++++++++++#+ESRCH+==+No+such+process
++++++++++++return+False
++++++++elif+err.errno+==+errno.EPERM:
++++++++++++#+EPERM+clearly+means+there's+a+process+to+deny+access+to
++++++++++++return+True
++++++++else:
++++++++++++#+According+to+"man+2+kill"+possible+error+values+are
++++++++++++#+(EINVAL,+EPERM,+ESRCH)
++++++++++++raise
++++else:
++++++++return+True|code-block|syntax|javascript|1408281|除非你使用pywin32、ctypes或C扩展模块，否则你不能在Windows上这样做。如果您不介意依赖于外部库，那么可以使用psutil|offset|length|1408282|>>>+import+psutil
>>>+psutil.pid_exists(2353)
True|1408283|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/giampaolo/psutil^0|0|0|0|1R|6|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@$K|10|L|11|1|12]]|A|$]]|$1|M|3|N|5|F|7|13|8|@]|9|@]|A|$G|H]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

mluebke code is not 100% correct; kill() can also raise EPERM (access denied) in which case that obviously means a process exists. This is supposed to work:

(edited as per Jason R. Coombs comments)

<pre><code>import errno
import os

def pid_exists(pid):
 """Check whether pid exists in the current process table.
 UNIX only.
 """
 if pid &lt; 0:
 return False
 if pid == 0:
 # According to "man 2 kill" PID 0 refers to every process
 # in the process group of the calling process.
 # On certain systems 0 is a valid PID but we have no way
 # to know that in a portable fashion.
 raise ValueError('invalid PID 0')
 try:
 os.kill(pid, 0)
 except OSError as err:
 if err.errno == errno.ESRCH:
 # ESRCH == No such process
 return False
 elif err.errno == errno.EPERM:
 # EPERM clearly means there's a process to deny access to
 return True
 else:
 # According to "man 2 kill" possible error values are
 # (EINVAL, EPERM, ESRCH)
 raise
 else:
 return True
</code></pre>

You can't do this on Windows unless you use pywin32, ctypes or a C extension module.
If you're OK with depending from an external lib you can use <a href="https://github.com/giampaolo/psutil" rel="noreferrer">psutil</a>:

<pre><code>&gt;&gt;&gt; import psutil
&gt;&gt;&gt; psutil.pid_exists(2353)
True
</code></pre>

blocks|key|1408317|text|结合Giampaolo+Rodolà's+answer+for+POSIX和mine+for+Windows，我得到了这样的结果：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1408318|import+os
if+os.name+==+'posix':
++++def+pid_exists(pid):
++++++++"""Check+whether+pid+exists+in+the+current+process+table."""
++++++++import+errno
++++++++if+pid+<+0:
++++++++++++return+False
++++++++try:
++++++++++++os.kill(pid,+0)
++++++++except+OSError+as+e:
++++++++++++return+e.errno+==+errno.EPERM
++++++++else:
++++++++++++return+True
else:
++++def+pid_exists(pid):
++++++++import+ctypes
++++++++kernel32+=+ctypes.windll.kernel32
++++++++SYNCHRONIZE+=+0x100000

++++++++process+=+kernel32.OpenProcess(SYNCHRONIZE,+0,+pid)
++++++++if+process+!=+0:
++++++++++++kernel32.CloseHandle(process)
++++++++++++return+True
++++++++else:
++++++++++++return+False|code-block|syntax|javascript|1408319|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/6940314/1777162|1|https://stackoverflow.com/a/17645054/1777162^0|2|Z|0|12|G|1|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]|$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]|Q|$5|L|M|N|C|$O|R]]]]

Combining <a href="https://stackoverflow.com/a/6940314/1777162">Giampaolo Rodolà's answer for POSIX</a> and <a href="https://stackoverflow.com/a/17645054/1777162">mine for Windows</a> I got this:

<pre><code>import os
if os.name == 'posix':
 def pid_exists(pid):
 """Check whether pid exists in the current process table."""
 import errno
 if pid &lt; 0:
 return False
 try:
 os.kill(pid, 0)
 except OSError as e:
 return e.errno == errno.EPERM
 else:
 return True
else:
 def pid_exists(pid):
 import ctypes
 kernel32 = ctypes.windll.kernel32
 SYNCHRONIZE = 0x100000

 process = kernel32.OpenProcess(SYNCHRONIZE, 0, pid)
 if process != 0:
 kernel32.CloseHandle(process)
 return True
 else:
 return False
</code></pre>

blocks|key|1408348|text|在Python+3.3%2B中，您可以使用异常名称而不是errno常量。Posix+version|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1408349|import+os

def+pid_exists(pid):+
++++if+pid+<+0:+return+False+#NOTE:+pid+==+0+returns+True
++++try:
++++++++os.kill(pid,+0)+
++++except+ProcessLookupError:+#+errno.ESRCH
++++++++return+False+#+No+such+process
++++except+PermissionError:+#+errno.EPERM
++++++++return+True+#+Operation+not+permitted+(i.e.,+process+exists)
++++else:
++++++++return+True+#+no+error,+we+can+send+a+signal+to+the+process|code-block|syntax|javascript|1408350|entityMap|0|LINK|mutability|MUTABLE|url|http://pubs.opengroup.org/onlinepubs/9699919799/functions/kill.html^0|Y|D|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

In Python 3.3+, you could use exception names instead of errno constants. <a href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/kill.html" rel="noreferrer">Posix version</a>:

<pre><code>import os

def pid_exists(pid): 
 if pid &lt; 0: return False #NOTE: pid == 0 returns True
 try:
 os.kill(pid, 0) 
 except ProcessLookupError: # errno.ESRCH
 return False # No such process
 except PermissionError: # errno.EPERM
 return True # Operation not permitted (i.e., process exists)
 else:
 return True # no error, we can send a signal to the process
</code></pre>

blocks|key|1623118|text|在ntrrgc的基础上，我已经增强了windows版本，以便它检查进程退出代码和权限：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1623119|def+pid_exists(pid):
++++"""Check+whether+pid+exists+in+the+current+process+table."""
++++if+os.name+==+'posix':
++++++++import+errno
++++++++if+pid+<+0:
++++++++++++return+False
++++++++try:
++++++++++++os.kill(pid,+0)
++++++++except+OSError+as+e:
++++++++++++return+e.errno+==+errno.EPERM
++++++++else:
++++++++++++return+True
++++else:
++++++++import+ctypes
++++++++kernel32+=+ctypes.windll.kernel32
++++++++HANDLE+=+ctypes.c_void_p
++++++++DWORD+=+ctypes.c_ulong
++++++++LPDWORD+=+ctypes.POINTER(DWORD)
++++++++class+ExitCodeProcess(ctypes.Structure):
++++++++++++_fields_+=+[+('hProcess',+HANDLE),
++++++++++++++++('lpExitCode',+LPDWORD)]

++++++++SYNCHRONIZE+=+0x100000
++++++++process+=+kernel32.OpenProcess(SYNCHRONIZE,+0,+pid)
++++++++if+not+process:
++++++++++++return+False

++++++++ec+=+ExitCodeProcess()
++++++++out+=+kernel32.GetExitCodeProcess(process,+ctypes.byref(ec))
++++++++if+not+out:
++++++++++++err+=+kernel32.GetLastError()
++++++++++++if+kernel32.GetLastError()+==+5:
++++++++++++++++#+Access+is+denied.
++++++++++++++++logging.warning("Access+is+denied+to+get+pid+info.")
++++++++++++kernel32.CloseHandle(process)
++++++++++++return+False
++++++++elif+bool(ec.lpExitCode):
++++++++++++#+print+ec.lpExitCode.contents
++++++++++++#+There+is+an+exist+code,+it+quit
++++++++++++kernel32.CloseHandle(process)
++++++++++++return+False
++++++++#+No+exit+code,+it's+running.
++++++++kernel32.CloseHandle(process)
++++++++return+True|code-block|syntax|javascript|1623120|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|$]]

Building upon ntrrgc's I've beefed up the windows version so it checks the process exit code and checks for permissions:

<pre><code>def pid_exists(pid):
 """Check whether pid exists in the current process table."""
 if os.name == 'posix':
 import errno
 if pid &lt; 0:
 return False
 try:
 os.kill(pid, 0)
 except OSError as e:
 return e.errno == errno.EPERM
 else:
 return True
 else:
 import ctypes
 kernel32 = ctypes.windll.kernel32
 HANDLE = ctypes.c_void_p
 DWORD = ctypes.c_ulong
 LPDWORD = ctypes.POINTER(DWORD)
 class ExitCodeProcess(ctypes.Structure):
 _fields_ = [ ('hProcess', HANDLE),
 ('lpExitCode', LPDWORD)]

 SYNCHRONIZE = 0x100000
 process = kernel32.OpenProcess(SYNCHRONIZE, 0, pid)
 if not process:
 return False

 ec = ExitCodeProcess()
 out = kernel32.GetExitCodeProcess(process, ctypes.byref(ec))
 if not out:
 err = kernel32.GetLastError()
 if kernel32.GetLastError() == 5:
 # Access is denied.
 logging.warning("Access is denied to get pid info.")
 kernel32.CloseHandle(process)
 return False
 elif bool(ec.lpExitCode):
 # print ec.lpExitCode.contents
 # There is an exist code, it quit
 kernel32.CloseHandle(process)
 return False
 # No exit code, it's running.
 kernel32.CloseHandle(process)
 return True
</code></pre>

blocks|key|1623154|text|这将适用于Linux，例如，如果您想要检查banshee是否正在运行...(banshee是一个音乐播放器)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1623155|import+subprocess

def+running_process(process):
++++"check+if+process+is+running.+<+process+>+is+the+name+of+the+process."

++++proc+=+subprocess.Popen(["if+pgrep+"+%2B+process+%2B+"+>/dev/null+2>&1;+then+echo+'True';+else+echo+'False';+fi"],+stdout=subprocess.PIPE,+shell=True)

++++(Process_Existance,+err)+=+proc.communicate()
++++return+Process_Existance

#+use+the+function
print+running_process("banshee")|code-block|syntax|javascript|1623156|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|$]]

This will work for Linux, for example if you want to check if banshee is running... (banshee is a music player)

<pre><code>import subprocess

def running_process(process):
 "check if process is running. &lt; process &gt; is the name of the process."

 proc = subprocess.Popen(["if pgrep " + process + " &gt;/dev/null 2&gt;&amp;1; then echo 'True'; else echo 'False'; fi"], stdout=subprocess.PIPE, shell=True)

 (Process_Existance, err) = proc.communicate()
 return Process_Existance

# use the function
print running_process("banshee")
</code></pre>

blocks|key|1623219|text|在Windows中，您可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1623220|import+ctypes
PROCESS_QUERY_INFROMATION+=+0x1000
def+checkPid(pid):
++++processHandle+=+ctypes.windll.kernel32.OpenProcess(PROCESS_QUERY_INFROMATION,+0,pid)
++++if+processHandle+==+0:
++++++++return+False
++++else:
++++++++ctypes.windll.kernel32.CloseHandle(processHandle)
++++return+True|code-block|syntax|javascript|1623221|首先，在这段代码中，您尝试获取一个进程的句柄，并给出pid。如果句柄有效，则关闭process的句柄并返回True；否则，返回False。OpenProcess文档：https://msdn.microsoft.com/en-us/library/windows/desktop/ms684320%2528v=vs.85%2529.aspx|offset|length|1623222|entityMap|0|LINK|mutability|MUTABLE|url|https://msdn.microsoft.com/en-us/library/windows/desktop/ms684320%2528v=vs.85%2529.aspx^0|0|0|2B|2B|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

In Windows, you can do it in this way:

<pre><code>import ctypes
PROCESS_QUERY_INFROMATION = 0x1000
def checkPid(pid):
 processHandle = ctypes.windll.kernel32.OpenProcess(PROCESS_QUERY_INFROMATION, 0,pid)
 if processHandle == 0:
 return False
 else:
 ctypes.windll.kernel32.CloseHandle(processHandle)
 return True
</code></pre>

First of all, in this code you try to get a handle for process with pid given. If the handle is valid, then close the handle for process and return True; otherwise, you return False. Documentation for OpenProcess: <a href="https://msdn.microsoft.com/en-us/library/windows/desktop/ms684320%28v=vs.85%29.aspx" rel="nofollow">https://msdn.microsoft.com/en-us/library/windows/desktop/ms684320%28v=vs.85%29.aspx</a>

blocks|key|1408619|text|我发现这个解决方案似乎在windows和linux上都能很好地工作。我使用psutil进行了检查。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1408620|import+psutil
import+subprocess
import+os
p+=+subprocess.Popen(['python',+self.evaluation_script],stdout=subprocess.PIPE,+stderr=subprocess.STDOUT)+

pid+=+p.pid

def+__check_process_running__(self,p):
++++if+p+is+not+None:
++++++++poll+=+p.poll()
++++++++if+poll+==+None:
++++++++++++return+True
++++return+False
++++
def+__check_PID_running__(self,pid):
++++"""
++++++++Checks+if+a+pid+is+still+running+(UNIX+works,+windows+we'll+see)
++++++++Inputs:
++++++++++++pid+-+process+id
++++++++returns:
++++++++++++True+if+running,+False+if+not
++++"""
++++if+(platform.system()+==+'Linux'):
++++++++try:
++++++++++++os.kill(pid,+0)
++++++++++++if+pid<0:+++++++++++++++#+In+case+code+terminates
++++++++++++++++return+False
++++++++except+OSError:
++++++++++++return+False+
++++++++else:
++++++++++++return+True
++++elif+(platform.system()+==+'Windows'):
++++++++return+pid+in+(p.pid+for+p+in+psutil.process_iter())|code-block|syntax|javascript|1408621|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|$]]

I found that this solution seems to work well in both windows and linux. I used psutil to check.
<pre><code>import psutil
import subprocess
import os
p = subprocess.Popen(['python', self.evaluation_script],stdout=subprocess.PIPE, stderr=subprocess.STDOUT) 

pid = p.pid

def __check_process_running__(self,p):
 if p is not None:
 poll = p.poll()
 if poll == None:
 return True
 return False
 
def __check_PID_running__(self,pid):
 &quot;&quot;&quot;
 Checks if a pid is still running (UNIX works, windows we'll see)
 Inputs:
 pid - process id
 returns:
 True if running, False if not
 &quot;&quot;&quot;
 if (platform.system() == 'Linux'):
 try:
 os.kill(pid, 0)
 if pid&lt;0: # In case code terminates
 return False
 except OSError:
 return False 
 else:
 return True
 elif (platform.system() == 'Windows'):
 return pid in (p.pid for p in psutil.process_iter())
</code></pre>

blocks|key|1408670|text|Windows的另一个选择是通过pywin32包：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1408671|pid+in+win32process.EnumProcesses()|code-block|syntax|javascript|1408672|win32process.EnumProcesses()返回当前正在运行的进程的PID。|1408673|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Another option for Windows is through the pywin32 package:
<pre><code>pid in win32process.EnumProcesses()
</code></pre>
The win32process.EnumProcesses() returns PIDs for currently running processes.

Is there a way to check to see if a pid corresponds to a valid process? I'm getting a pid from a different source other than from <code>os.getpid()</code> and I need to check to see if a process with that pid doesn't exist on the machine. 

I need it to be available in Unix and Windows. I'm also checking to see if the PID is NOT in use.

How to check if there exists a process with a given pid in Python?

Windows

Python

Linux

Unix

有没有办法检查pid是否对应于有效的进程？我从os.getpid()以外的其他来源获取pid，我需要检查机器上是否不存在具有该pid的进程。我需要它在Unix和Windows中可用。我还在检查PID是否未被使用。

问如何检查Python中是否存在具有给定pid的进程？
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问如何检查Python中是否存在具有给定pid的进程？EN

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