I have two .py programme. I call second .py program , the second program solves a problem . So ı want to get that solution to first one and use . for example:
1.py:
call 2.py
y= x+2
2.py:
x = 2+2
You need to import the .py file into another file
Running it in OS does not get the variable in your new file
Use
from module import function
You can then call the function from this new file and print the value that it returns
Use the subprocess module and create a pipe. Then you can pickle the variable and send it through the pipe (see documentation of subprocess).
Here is an example:
module for communication communicate.py:
import sys
import subprocess as sp
import cPickle
BEGIN = 'pickle_begin'
def send_and_exit(x):
sys.stdout.write(BEGIN + cPickle.dumps(x))
sys.stdout.flush()
sys.exit(0)
def execute_and_receive(filename):
p = sp.Popen(["python", filename], stdout=sp.PIPE)
(out, err) = p.communicate()
return cPickle.loads(out[out.find(BEGIN) + len(BEGIN):])
1.py:
from communicate import *
x = execute_and_receive("2.py")
y = x + 2
2.py:
from communicate import *
x = 2 + 2
send_and_exit(x)
To make sure, you start unpickling at the correct point of the stdout stream I recommend to set a marker, like I did with the BEGIN string. Probably there are more elegant solutions, if so, I'm interested as well.
Related
I have a file which connects a database and fetches the result. Now the file must be ran using python 3 and my project uses python 2.7. So I run the file as a command line using subprocess module. Here is how I call the file.
import subprocess
import ast
def execute_python3(param):
param = param.replace("\\", "")
param = "\"" + param + "\""
cmd = "python3 " + "get_db_result.py" + " " + param
result = subprocess.check_output(cmd, shell=True)
return ast.literal_eval(result)
execute_python3(sql_query)
Here in the command, I am passing sql query to the get_db_result file.
The get_db_result.py file looks something like this
import sys
def get_result():
param = sys.argv[1]
'''
Logic to get result from db
'''
result = db_output
print(result)
if __name__ == "__main__":
get_result()
Now the issue is when I fetch the output from db, I have to do a print for the output to be captured by the subprocess module. This makes it difficult to parse the output to be used by program for further work. For example, when I receive an output like this
"[(u'Delhi', 20199330), (u'Mumbai', 134869470), (u'Kolkata', 6678446)]"
This is a string list of tuples which can be converted to list of tuples by doing something like ast.literal_eval(result)
But sometimes I get output like this
"[(datetime.date(2019, 5, 27), 228.168093587), (datetime.date(2019, 5, 28), 228.834493641)]"
Here ast doesn't understand datetime. Even json.loads() doesn't work on this.
How can I capture the output from a file without having to use print and simply return it back to subprocess as it is. Is it even possible?
You need to serialize and deserialize the data on both ends. Simplest solution would be to use Python's pickle module and hope the types that are serialized on the Python 3 end, are similar enough to those on the deserializing Python 2 end. You need to specify the used protocol on the sending end to a version understood by the receiving end:
Receiver with safer call of subprocess (no shell process in between):
#!/usr/bin/env python
import pickle
import subprocess
def execute_python3(param):
result = subprocess.check_output(['python3', 'get_db_result.py', param])
return pickle.loads(result)
def main():
execute_python3(sql_query)
if __name__ == '__main__':
main()
Sender, explicitly choosing a pickle protocol still understood by Python 2:
#!/usr/bin/env python3
import sys
import pickle
def get_result():
param = sys.argv[1]
'''
Logic to get result from db
'''
result = db_output
pickle.dump(result, sys.stdout.buffer, protocol=2)
if __name__ == '__main__':
get_result()
If this doesn't work because of differences in the (de)serialized objects between Python 2 and 3, you have to fall back to explicitly (de)serialize the data, for example in JSON, as suggested by a comment from Jay.
I am trying to use Python to open another file. This file is going to start up a socket and create threads for listening for additional connections, and threads for sending/receiving data. The main thread will not return.
However, if the setup of sockets fail, I want to return a error code to the other python script that executed the subprocess.
main.py
py3output = subprocess.check_output(['python3', 'py3.py'])
print('py3 said:' + str(py3output))
py3.py
def returnme():
return 10
returnme()
When I run this, it prints:
py3 said:b''
I am just trying to figure out how to get the return value back to the main calling program.
To return an exit code n back to the OS, you need sys.exit(n). But seems like you do not want to check the exit code but the stdout otput. So your program might need to rewrite to:
def returnme():
return 10
print(returnme())
You should only return a string as a standard output using following code:
sample.py
import sys
def returnme():
sys.stdout.write(str(10))
sys.stdout.flush()
returnme()
main.py
from subprocess import check_output
output = check_output(['python','sample.py'])
print('Sample.py says :' + output)
I have been looking all over the internet for a way to find a way to get UUID for a computer and set it as a variable in python.
Some of the ways I tried doing didn't work.
Original idea:
import os
x = os.system("wmic diskdrive get serialnumber")
print(x)
However this does not work, and only returns 0.
I am wondering if their is a way i can find a unique Harddrive ID or any other type of identifier in python.
The os.system function returns the exit code of the executed command, not the standard output of it.
According to Python official documentation:
On Unix, the return value is the exit status of the process encoded in the format specified for wait().
On Windows, the return value is that returned by the system shell
after running command.
To get the output as you want, the recommended approach is to use some of the functions defined in the subprocess module. Your scenario is pretty simple, so subprocess.check_output works just fine for it.
You just need to replace the code you posted code with this instead:
import subprocess
x = subprocess.check_output('wmic csproduct get UUID')
print(x)
If the aim is to get the serial number of the HDD, then one can do:
In Linux (replace /dev/sda with the block disk identifier for which you want the info):
>>> import os
>>> os.popen("hdparm -I /dev/sda | grep 'Serial Number'").read().split()[-1]
In Windows:
>>> import os
>>> os.popen("wmic diskdrive get serialnumber").read().split()[-1]
for windows i do work with this one and it works perfectly:
import subprocess
UUID = str(subprocess.check_output('wmic csproduct get UUID'),'utf-8').split('\n')[1].strip()
print(UUID)
For windows:
import wmi
import os
def get_serial_number_of_system_physical_disk():
c = wmi.WMI()
logical_disk = c.Win32_LogicalDisk(Caption=os.getenv("SystemDrive"))[0]
partition = logical_disk.associators()[1]
physical_disc = partition.associators()[0]
return physical_disc.SerialNumber
For Linux try this:
def get_uuid():
dmidecode = subprocess.Popen(['dmidecode'],
stdout=subprocess.PIPE,
bufsize=1,
universal_newlines=True
)
while True:
line = dmidecode.stdout.readline()
if "UUID:" in str(line):
uuid = str(line).split("UUID:", 1)[1].split()[0]
return uuid
if not line:
break
my_uuid = get_uuid()
print("My ID:", my_uuid)
There is an external program A.
I want to write a script that does some action if the called external program A does not bring up any output(stout).
How is this possible in bash or python?
You can use the subprocess module which allows you to execute system calls and store its output in variables which can be used later on.
#!/usr/bin/python
import subprocess as sub
ur_call = '<your system call here>'
p = sub.Popen(ur_call, stdout=sub.PIPE,stderr=sub.PIPE)
output, errors = p.communicate()
if len(output) == 0 and len(errors) == 0:
pass # Do something
In a Bash-script, you could redirect the output to a file, and if the length of the file is zero then there was no output.
If the script that sometimes gives output is no.sh then you can do this in Python:
import os
x = os.popen("./no.sh")
y = x.read()
if y:
print "Got output"
Hello i am using the subprocess.Popen() class and i succesful execute commands on the terminal, but when i try to execute programs for example an script written on Python and i try to pass arguments the system fails.
This is the code:
argPath = "test1"
args = open(argPath, 'w')
if self.extract.getByAttr(self.block, 'name', 'args') != None:
args.write("<request>"+self.extract.getByAttr(self.block, 'name', 'args')[0].toxml()+"</request>")
else:
args.write('')
car = Popen(shlex.split('python3.1 /home/hidura/webapps/karinapp/Suite/ForeingCode/saveCSS.py', stdin=args, stdout=subprocess.PIPE, stderr=subprocess.PIPE))
args.close()
dataOut = car.stdout.read().decode()
log = car.stderr.read().decode()
if dataOut!='':
return dataOut.split('\n')
elif log != '':
return log.split('\n')[0]
else:
return None
And the code from the saveCSS.py
from xml.dom.minidom import parseString
import os
import sys
class savCSS:
"""This class has to save
the changes on the css file.
"""
def __init__(self, args):
document = parseString(args)
request = document.firstChild
address = request.getElementsByTagName('element')[0]
newdata = request.getElementsByTagName('element')[1]
cssfl = open("/webapps/karinapp/Suite/"+address.getAttribute('value'), 'r')
cssData = cssfl.read()
cssfl.close()
dataCSS = ''
for child in newdata.childNodes:
if child.nodeType == 3:
dataCSS += child.nodeValue
nwcssDict = {}
for piece in dataCSS.split('}'):
nwcssDict[piece.split('{')[0]] = piece.split('{')[1]
cssDict = {}
for piece in cssData.split('}'):
cssDict[piece.split('{')[0]] = piece.split('{')[1]
for key in nwcssDict:
if key in cssDict == True:
del cssDict[key]
cssDict[key] = nwcssDict[key]
result = ''
for key in cssDict:
result += key+"{"+cssDict[key]+"}"
cssfl = open(cssfl.name, 'a')
cssfl.write(result)
cssfl.close()
if __name__ == "__main__":
savCSS(sys.stdin)
BTW: There's no output...
Thanks in advance.
OK, I'm ignoring that your code doesn't run (neither the script you try to execute, not the main script actually works), and looking at what you are doing:
It does execute the script, or you would get an error, like "bin/sh: foo: not found".
Also you seem to be using an open file as stdin after you have written to it. That doesn't work.
>>> thefile = open('/tmp/foo.txt', 'w')
>>> thefile.write("Hej!")
4
>>> thefile.read()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IOError: not readable
You need to close the file, and reopen it as a read file. Although better in this case would be to use StringIO, I think.
To talk to the subprocess, you use communicate(), not read() on the pipes.
I'm not sure why you are using shell=True here, it doesn't seem necessary, I would remove it if I was you, it only complicates stuff unless you actually need the shell to do things.
Specifically you should not split the command into a list when using shell=True. What your code is actually doing, is starting a Python prompt.
You should rather use communicate() instead of .stdout.read().
And the code you posted isn't even correct:
Popen(shlex.split('python3.1 /home/hidura/webapps/karinapp/Suite/ForeingCode/saveCSS.py', stdin=args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
There's a missing parenthesis, and from the stdout/stderr parameters, it's clear that you get no output to the console, but rather into pipes (if that's what you meant by "There's no output...").
Your code will actually work on Windows, but on Linux you must remove the shell=True parameter. You should always omit that parameter if you provide the full command line yourself (as a sequence).