Running A Bat File Though Python In Current Process

June 17, 2022 Post a Comment

I am attempting to build a large system through a python script. I first need to set up the environment for Visual Studio. Having problems I decided to see if I could just set up

Solution 1:

I had the exact same problem as you. I was trying to run vcvarsall.bat as part of a build script written in python and I needed the environment created by vcvarsall. I found a way to do it. First create a wrapper script called setup_environment.bat:

call "C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\vcvarsall.bat" amd64
set > environment.txt

Then in your python script where you would have called vcvarsall.bat, run the wrapper script, then read the environment variables from the text file into your current environment:

    this_dir = os.path.dirname(os.path.realpath(__file__)) # path of the currently executing script
    os.system('call ' + this_dir + '\setup_environment.bat') # run the wrapper script, creates environment.txt
    f = open('environment.txt','r')
    lines = f.read().splitlines()
    f.close()
    os.remove('environment.txt')
    for line in lines:
        pair = line.split('=',1)
        os.environ[pair[0]] = pair[1]

Solution 2:

Here is a simple example, should work out of box:

import os
import platform


def init_vsvars():
    vswhere_path = r"%ProgramFiles(x86)%/Microsoft Visual Studio/Installer/vswhere.exe"
    vswhere_path = os.path.expandvars(vswhere_path)
    if not os.path.exists(vswhere_path):
        raise EnvironmentError("vswhere.exe not found at: %s", vswhere_path)

    vs_path = os.popen('"{}" -latest -property installationPath'.format(vswhere_path)).read().rstrip()
    vsvars_path = os.path.join(vs_path, "VC\\Auxiliary\\Build\\vcvars64.bat")

    output = os.popen('"{}" && set'.format(vsvars_path)).read()

    for line in output.splitlines():
        pair = line.split("=", 1)
        if(len(pair) >= 2):
            os.environ[pair[0]] = pair[1]

if "windows" in platform.system().lower():
    init_vsvars()
    os.system("where cl.exe")

Please note that environment variables don't have effect after python script exits.

Solution 3:

What you are trying to do won't work. vcvarsall.bat sets environment variables, which only work inside a particular process. And there is no way for a Python process to run a CMD.exe process within the same process space.

I have several solutions for you.

One is to run vcvarsall.bat, then figure out all the environment variables it sets and make Python set them for you. You can use the command set > file.txt to save all the environment variables from a CMD shell, then write Python code to parse this file and set the environment variables. Probably too much work.

The other is to make a batch file that runs vcvarsall.bat, and then fires up a new Python interpreter from inside that batch file. The new Python interpreter will be in a new process, but it will be a child process under the CMD.exe process, and it will inherit all the environment variables.

Or, hmm. Maybe the best thing is just to write a batch file that runs vcvarsall.bat and then runs the devenv command. Yeah, that's probably simplest, and simple is good.

Baca Juga

The important thing to note is that in the Windows batch file language (and DOS batch file before it), when you execute another batch file, variables set by the other batch file are set in the same environment. In *NIX you need to use a special command source to run a shell script in the same environment, but in batch that's just how it works. But you will never get variables to persist after a process has terminated.

Solution 4:

Building on the answer by @derekswanson08 I came up with this which is a bit more fully-fledged. Uses wvwhere.exe which comes with VS 2017.

def init_vsvars():
    cprint("")
    cprint_header("Initializing vs vars")

    if "cygwin" in platform.system().lower():
        vswhere_path = "${ProgramFiles(x86)}/Microsoft Visual Studio/Installer/vswhere.exe"
    else:
        vswhere_path = r"%ProgramFiles(x86)%/Microsoft Visual Studio/Installer/vswhere.exe"
    vswhere_path = path.expandvars(vswhere_path)
    if not path.exists(vswhere_path):
        raise EnvironmentError("vswhere.exe not found at: %s", vswhere_path)

    vs_path = common.run_process(".", vswhere_path,
                                 ["-latest", "-property", "installationPath"])
    vs_path = vs_path.rstrip()

    vsvars_path = os.path.join(vs_path, "VC/Auxiliary/Build/vcvars64.bat")

    env_bat_file_path = "setup_build_environment_temp.bat"
    env_txt_file_path = "build_environment_temp.txt"
    with open(env_bat_file_path, "w") as env_bat_file:
        env_bat_file.write('call "%s"\n' % vsvars_path)
        env_bat_file.write("set > %s\n" % env_txt_file_path)

    os.system(env_bat_file_path)
    with open(env_txt_file_path, "r") as env_txt_file:
        lines = env_txt_file.read().splitlines()

    os.remove(env_bat_file_path)
    os.remove(env_txt_file_path)
    for line in lines:
        pair = line.split("=", 1)
        os.environ[pair[0]] = pair[1]

Solution 5:

What you should be using is a module in the standard library called subprocess

I have linked you to an example in the standard library here.

Here is an example with your situation.

import shlex, subprocess
args = shlex.split(your_command)
p = subprocess.Popen(args)

That should execute it also return stderr if you need to know what happened with the call. your command might even be a third bat file that encompasses the two bat files so you get all the environment variables.

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