要从我的python脚本启动程序，我使用以下方法:
def execute(command):
process = subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
output = process.communicate()[0]
exitCode = process.returncode
if (exitCode == 0):
return output
else:
raise ProcessException(command, exitCode, output)
所以当我启动一个进程，比如进程。执行("mvn clean install")时，我的程序会一直等待，直到进程完成，只有到那时我才能得到程序的完整输出。这是恼人的，如果我正在运行一个进程，需要一段时间才能完成。
我能让我的程序一行一行地写进程输出吗，在循环结束之前轮询进程输出什么的?
我找到了这篇文章，可能与此有关。
当前回答
import time
import sys
import subprocess
import threading
import queue
cmd='esptool.py --chip esp8266 write_flash -z 0x1000 /home/pi/zero2/fw/base/boot_40m.bin'
cmd2='esptool.py --chip esp32 -b 115200 write_flash -z 0x1000 /home/pi/zero2/fw/test.bin'
cmd3='esptool.py --chip esp32 -b 115200 erase_flash'
class ExecutorFlushSTDOUT(object):
def __init__(self,timeout=15):
self.process = None
self.process_output = queue.Queue(0)
self.capture_output = threading.Thread(target=self.output_reader)
self.timeout=timeout
self.result=False
self.validator=None
def output_reader(self):
start=time.time()
while self.process.poll() is None and (time.time() - start) < self.timeout:
try:
if not self.process_output.full():
line=self.process.stdout.readline()
if line:
line=line.decode().rstrip("\n")
start=time.time()
self.process_output.put(line)
if self.validator:
if self.validator in line: print("Valid");self.result=True
except:pass
self.process.kill()
return
def start_process(self,cmd_list,callback=None,validator=None,timeout=None):
if timeout: self.timeout=timeout
self.validator=validator
self.process = subprocess.Popen(cmd_list,stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)
self.capture_output.start()
line=None
self.result=False
while self.process.poll() is None:
try:
if not self.process_output.empty():
line = self.process_output.get()
if line:
if callback:callback(line)
#print(line)
line=None
except:pass
error = self.process.returncode
if error:
print("Error Found",str(error))
raise RuntimeError(error)
return self.result
execute = ExecutorFlushSTDOUT()
def liveOUTPUT(line):
print("liveOUTPUT",line)
try:
if "Writing" in line:
line=''.join([n for n in line.split(' ')[3] if n.isdigit()])
print("percent={}".format(line))
except Exception as e:
pass
result=execute.start_process(cmd2,callback=liveOUTPUT,validator="Hash of data verified.")
print("Finish",result)
其他回答
这至少在Python3.4中是有效的
import subprocess
process = subprocess.Popen(cmd_list, stdout=subprocess.PIPE)
for line in process.stdout:
print(line.decode().strip())
在@jfs的出色回答的基础上，这里有一个完整的工作示例供您使用。要求Python 3.7或更新版本。
sub.py
import time
for i in range(10):
print(i, flush=True)
time.sleep(1)
main.py
from subprocess import PIPE, Popen
import sys
with Popen([sys.executable, 'sub.py'], bufsize=1, stdout=PIPE, text=True) as sub:
for line in sub.stdout:
print(line, end='')
注意子脚本中使用的flush参数。
这个PoC不断地从进程中读取输出，并可以在需要时访问。只有最后一个结果被保留，所有其他输出都被丢弃，因此防止了PIPE的内存不足:
import subprocess
import time
import threading
import Queue
class FlushPipe(object):
def __init__(self):
self.command = ['python', './print_date.py']
self.process = None
self.process_output = Queue.LifoQueue(0)
self.capture_output = threading.Thread(target=self.output_reader)
def output_reader(self):
for line in iter(self.process.stdout.readline, b''):
self.process_output.put_nowait(line)
def start_process(self):
self.process = subprocess.Popen(self.command,
stdout=subprocess.PIPE)
self.capture_output.start()
def get_output_for_processing(self):
line = self.process_output.get()
print ">>>" + line
if __name__ == "__main__":
flush_pipe = FlushPipe()
flush_pipe.start_process()
now = time.time()
while time.time() - now < 10:
flush_pipe.get_output_for_processing()
time.sleep(2.5)
flush_pipe.capture_output.join(timeout=0.001)
flush_pipe.process.kill()
print_date.py
#!/usr/bin/env python
import time
if __name__ == "__main__":
while True:
print str(time.time())
time.sleep(0.01)
输出:你可以清楚地看到只有大约2.5s的输出间隔。
>>>1520535158.51
>>>1520535161.01
>>>1520535163.51
>>>1520535166.01
在Python 3.6中，我使用了这个:
import subprocess
cmd = "command"
output = subprocess.call(cmd, shell=True)
print(process)
要回答最初的问题，IMO的最佳方法是直接将子进程stdout重定向到程序的stdout(可选地，对于stderr也可以这样做，如下例所示)
p = Popen(cmd, stdout=sys.stdout, stderr=sys.stderr)
p.communicate()
