i would like to pass values from python to a c++ program for an encryption from inside a python program and then return the value from there to the python program . how to do it?
If you want to use some existing Unix-style command line utility that reads from stdin and writes to stdout, you can use subprocess.Popen by using Popen.communicate():
import subprocess
p = subprocess.Popen(["/your/app"], stdin=subprocess.PIPE, stdout=subprocess.PIPE)
output = p.communicate(input)[0]
As said msw in the other post, the proper solution is using PyObject.
If you want to have a two-way communication between C++ & Python, Boost Python would be interesting for you. Take a look at website Boost Python,
This post would also be interesting:
How to expose a C++ class to Python without building a module
Related
I am working with a command line tool called 'ideviceinfo' (see https://github.com/libimobiledevice) to help me to quickly get back serial, IMEI and battery health information from the iOS device I work with daily. It executes much quicker than Apple's own 'cfgutil' tools.
Up to know I have been able to develop a more complicated script than the one shown below in PyCharm (my main IDE) to assign specific values etc to individual variables and then to use something like to pyclip and pyautogui to help automatically paste these into the fields of the database app we work with. I have also been able to use the simplified version of the script both in Mac OS X terminal and in the python shell without any hiccups.
I am looking to use AppleScript to help make running the script as easy as possible.
When I try to use Applescript's "do shell script 'python script.py'" I just get back a string of lenght zero when I call 'ideviceinfo'. The exact same thing happens when I try to build an Automator app with a 'Run Shell Script' component for "python script.py".
I have tried my best to isolate the problem down. When other more basic commands such as 'date' are called within the script they return valid strings.
#!/usr/bin/python
import os
ideviceinfoOutput = os.popen('ideviceinfo').read()
print ideviceinfoOutput
print len (ideviceinfoOutput)
boringExample = os.popen('date').read()
print boringExample
print len (boringExample)
I am running Mac OS X 10.11 and am on Python 2.7
Thanks.
I think I've managed to fix it on my own. I just need to be far more explicit about where the 'ideviceinfo' binary (I hope that's the correct term) was stored on the computer.
Changed one line of code to
ideviceinfoOutput = os.popen('/usr/local/bin/ideviceinfo').read()
and all seems to be OK again.
I have multiple python scripts, each with print statements and prompts for input. I run these scripts from a single python script as below.
os.system('python script1.py ' + sys.argv[1])
os.system('python script2.py ' + sys.argv[1]).....
The run is completed successfully, however, when I run all the scripts from a single file, I no longer see any print statements or prompts for input on the run console. Have researched and attempted many different ways to get this to work w/o success. Help would be much appreciated. Thanks.
If I understand correctly you want to run multiple python scripts synchronously, i.e. one after another.
You could use a bash script instead of python, but to answer your question of starting them from python...
Checkout out the subprocess module: https://docs.python.org/3.4/library/subprocess.html
In particular the call method, it accepts a stdin and stdout which you can pass sys.stdin and sys.stdout to.
import sys
import subprocess
subprocess.call(['python', 'script1.py', sys.argv[1]], stdin=sys.stdin, stdout=sys.stdout)
subprocess.call(['python', 'script2.py', sys.argv[1]], stdin=sys.stdin, stdout=sys.stdout)
^
This will work in python 2.7 and 3, another way of doing this is by importing your file (module) and calling the methods in it. The difference here is that you're no longer running the code in a separate process.
subroutine.py
def run_subroutine():
name = input('Enter a name: ')
print(name)
master.py
import subroutine
subroutine.run_subroutine()
I want to extend my application, which is written in C++ using python scripts (extensions). I originally wanted to use TCL for that, just like they do in xchat, for example, but later I decided to use python, because it seems to be quite popular for whatever reasons.
However, I am failing to load and execute even very simple python script. I followed http://docs.python.org/2/extending/embedding.html
When I give a filename of script that I want to load as argument to pName, the error I get from PyErr_Print is: ImportError: Import by filename is not supported.
Reading the documentation, I figured I might need to run PyImport_ExecCodeModule, however this C function requires 2 arguments, 1 is char * (probably a name of module), other one is compiled python code, which according to docs I can get by calling python function compile(). Unfortunately it doesn't say how do I call this python function using C api's in my C++ code. Ideally I would imagine to do something like
PyObject *code = PyCompile("print (\"hello :)\"");
but I couldn't find any function like PyCompile, neither any other C-api function that would simply allowed me to execute python internal function (like compile) and grab its output as PyObject.
So, question is: how can I easily load a python script from a file (something.py) and execute it within my application using the embedded python interpretor?
I have been having problems trying to run an external program from a python program that was generated from a trigger in a postgres 9.2 database. The trigger works. It writes to a file. I had tried just running the external program but the permissions would not allow it to run. I was able to create a folder (using os.system(“mkdir”) ). The owner of the folder is NETWORK SERVICE.
I need to run a program called sdktest. When I try to run it no response happens so I think that means that the python program does not have enough permissions (with an owner of NETWORK SERVICE) to run it.
I have been having my program copy files that it needs into that directory so they would have the correct permissions and that has worked to some degree but the program that I need to run is the last one and it is not running because it does not have enough permissions.
My python program runs a C++ program called PG_QB_Connector which calls sdktest.
Is there any way I can change the owner of the process to be a “normal” owner? Is there a better way to do this? Basically I just need to have this C++ program have eniough perms to run correctly.
BTW, when I run the C++ program by hand, the line that runs the sdktest program runs correctly, however, when I run it from the postgres/python it does not do anything...
I have Windows 7, python 3.2. The other 2 questions that I asked about this are located here and here
The python program:
CREATE or replace FUNCTION scalesmyone (thename text)
RETURNS int
AS $$
a=5
f = open('C:\\JUNK\\frompython.txt','w')
f.write(thename)
f.close()
import os
os.system('"mkdir C:\\TEMPWITHOWNER"')
os.system('"mkdir C:\\TEMPWITHOWNER\\addcustomer"')
os.system('"copy C:\\JUNK\\junk.txt C:\\TEMPWITHOWNER\\addcustomer"')
os.system('"copy C:\\BATfiles\\junk6.txt C:\\TEMPWITHOWNER\\addcustomer"')
os.system('"copy C:\\BATfiles\\run_addcust.bat C:\\TEMPWITHOWNER\\addcustomer"')
os.system('"copy C:\\Workfiles\\PG_QB_Connector.exe C:\\TEMPWITHOWNER\\addcustomer"')
os.system('"copy C:\\Workfiles\\sdktest.exe C:\\TEMPWITHOWNER\\addcustomer"')
import subprocess
return_code = subprocess.call(["C:\\TEMPWITHOWNER\\addcustomer\\PG_QB_Connector.exe", '"hello"'])
$$ LANGUAGE plpython3u;
The C++ program that is called from the python program and calls sdktest.exe is below
command = "copy C:\\Workfiles\\AddCustomerFROMWEB.xml C:\\TEMPWITHOWNER\\addcustomer\\AddCustomerFROMWEB.xml";
system(command.c_str());
//everything except for the qb file is in my local folder
command = "C:\\TEMPWITHOWNER\\addcustomer\\sdktest.exe \"C:\\Users\\Public\\Documents\\Intuit\\QuickBooks\\Company Files\\Shain Software.qbw\" C:\\TEMPWITHOWNER\\addcustomer\\AddCustomerFROMWEB.xml C:\\TEMPWITHOWNER\\addcustomer\\outputfromsdktestofaddcust.xml";
system(command.c_str());
It sounds like you want to invoke a command-line program from within a PostgreSQL trigger or function.
A usually-better alternative is to have the trigger send a NOTIFY and have a process with a PostgreSQL connection LISTENing for notifications. When a notification comes in, the process can start your program. This is the approach I would recommend; it's a lot cleaner and it means your program doesn't have to run under PostgreSQL's user ID. See NOTIFY and LISTEN.
If you really need to run commands from inside Pg:
You can use PL/Pythonu with os.system or subprocess.check_call; PL/Perlu with system(); etc. All these can run commands from inside Pg if you need to. You can't invoke programs directly from PostgreSQL, you need to use one of the 'untrusted' (meaning fully privileged, not sandboxed) procedural languages to invoke external executables. PL/TCL can probably do it too.
Update:
Your Python code as shown above has several problems:
Using os.system in Python to copy files is just wrong. Use the shutil library: http://docs.python.org/3/library/shutil.html to copy files, and the simple os.mkdir command to create directories.
The double-layered quoting looks wrong; didn't you mean to quote only each argument not the whole command? You should be using subprocess.call instead of os.system anyway.
Your final subprocess.call invocation appears OK, but fails to check the error code so you'll never know if it went wrong; you should use subprocess.check_call instead.
The C++ code also appears to fail to check for errors from the system() invocations so you'll never know if the command it runs fails.
Like the Python code, copying files in C++ by using the copy shell command is generally wrong. Microsoft Windows provides the CopyFile function for this; equivalents or alternatives exist on other platforms and you can use portable-but-less-efficient stream copying too.
I have a bit of an issue here. I have a Python script which calls binaries compiled from C++. The Python script has its own set of outputs (to standard out and error), which are easily disable-able. The C++ binaries have their own set of outputs (to standard out and error, among others) as well; the source can be altered, but I am not the original author. This is an issue because I do not want the C++ output in my final program, and I also don't want future users to need to edit the C++ source.
What I'd like to be able to do is have some Python method which will catch the C++ code's output that is sent to standard out or error. Is this possible? If so, could someone point me in the right direction?
Thank you!!
One way to do this is:
Duplicate in python the file descriptors for stdout and stderr using os.dup.
Redirect the original stdout and stderr using reopen (from C's stdio) to write to a file of your choice.
Note: reopen isn't available directly from python, but you should be able to call it as in the example below or using any other wrapper available.
After this is done:
Every write to cout and cerr in C++ will write to the output files.
Every print statement in python will write to the output files.
However, since the original descriptors are duplicated, you can still (see example below):
Print to the original stdout/stderr using sdout.write and stdout.err
Use logging methods after configuring properly the stream parameter
The following code uses instant library to test real C++ code that is wrapped into python using SWIG and that should be similar to the library that you have:
import sys, os
import logging
from instant import inline
print 'This is printed from python to stdout'
stdout = os.fdopen(os.dup(sys.stdout.fileno()), 'w')
stderr = os.fdopen(os.dup(sys.stderr.fileno()), 'w')
logging.basicConfig(stream=stderr, level=logging.DEBUG)
redirect = inline("""
void redirect(void) {
freopen("my_stdout.txt", "w", stdout);
freopen("my_stderr.txt", "w", stderr);
}
""")
redirect()
cout = inline("""
void cout(void) {
std::cout << "This is written from C++ to my_stdout.txt" << std::endl;
std::cerr << "This is written from C++ to my_stderr.txt" << std::endl;
}
""")
cout()
print 'This is written from python to my_stdout.txt'
stdout.write('This is printed from python to stdout\n')
stderr.write('This is printed from python to stderr\n')
logging.info('This is printed to stderr from python using logging')
The output for this example is:
$ python test.py
This is printed from python to stdout
This is printed from python to stdout
This is printed from python to stderr
INFO:root:This is printed to stderr from python using logging
$ cat my_stdout.txt
This is written from C++ to my_stdout.txt
This is written from python to my_stdout.txt
$ cat my_stderr.txt
This is written from C++ to my_stderr.txt
Note: First time the code is executed, you might get gcc compilation messages (I've removed them to make the example clearer).
Are you using subprocess to compile the C++? If so, you can set where stderr and stdout go:
nowhere = StringIO()
subprocess.call("exit 1", shell=True, stdout=nowhere, stderr=nowhere)