Launch a totally independent process from Python

Launch a totally independent process from Python

To launch a totally independent process from Python, you can use the subprocess module. This module allows you to start and control external processes independently. Here's how you can do it:

import subprocess

# Define the command you want to run as a list
# For example, to run "python script.py arg1 arg2" as an independent process:
command = ["python", "script.py", "arg1", "arg2"]

# Launch the independent process
process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

# Optionally, you can wait for the process to finish
# (if you want to wait for the process to complete)
# process.wait()

# You can also access the process' output if needed
# stdout, stderr = process.communicate()

# The process is now running independently
# Your Python script can continue to execute other code

In this example:

  1. You define the command you want to run as a list called command. This list should contain the executable or script you want to run and any command-line arguments it requires.

  2. You use subprocess.Popen() to launch the process. The stdout=subprocess.PIPE and stderr=subprocess.PIPE arguments are used to capture the standard output and standard error of the process. You can remove these if you don't need to capture the output.

  3. The Popen() function returns a process object (process) that you can use to interact with the launched process.

  4. If you want to wait for the process to finish before proceeding with your Python script, you can uncomment process.wait(). If you want to capture the output of the process, you can uncomment the communicate() line.

By using subprocess.Popen(), you can launch a completely independent process from your Python script that runs concurrently with your script. This is useful for running external programs, scripts, or other processes independently.

Examples

  1. How to launch a background process in Python? Description: This query aims to understand how to start a process in Python that runs independently in the background.

    import subprocess

subprocess.Popen(["your_command_here"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)

    Using subprocess.Popen() allows you to launch a process without waiting for it to complete. Redirecting stdout and stderr to subprocess.DEVNULL suppresses output.

  2. Python spawn process and detach Description: Users might seek information on spawning a process from Python and detaching it from the parent process.

    import os

pid = os.fork()
if pid == 0:
    # Child process
    os.system("your_command_here")

    This code uses os.fork() to create a child process. The child process then executes the desired command independently from the parent.

  3. Run Python script as daemon process Description: This query may focus on running a Python script as a daemon process, detached from the terminal.

    import os

pid = os.fork()
if pid > 0:
    # Exit parent process
    os._exit(0)

# Now the script continues running in the child process

    By forking the process, the script can detach itself from the terminal and continue running as a daemon.

  4. Python start process and detach from terminal Description: Users may look for ways to initiate a process from Python and detach it from the terminal.

    import subprocess

subprocess.Popen(["your_command_here"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL, close_fds=True)

    In this code, close_fds=True ensures that all file descriptors except for standard input, output, and error streams are closed in the child process, allowing it to detach from the terminal.

  5. Launch a background process in Python Description: This query is about starting a process in Python that runs independently in the background.

    import subprocess

subprocess.Popen(["your_command_here"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)

    By redirecting stdout and stderr to subprocess.PIPE, the process runs independently, and its output can be captured if needed.

  6. Execute Python script as a detached process Description: This query may seek ways to execute a Python script as a separate, detached process.

    import subprocess

subprocess.Popen(["python", "your_script.py"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL, close_fds=True)

    By invoking subprocess.Popen() with the Python interpreter and the script's name as arguments, the script can run independently from the parent process.

  7. Spawn a process in Python and leave it running Description: Users might want to spawn a process in Python and ensure it continues running independently.

    import subprocess

subprocess.Popen(["your_command_here"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL, close_fds=True)

    This code launches the specified command and detaches it from the terminal using subprocess.Popen().

  8. Run shell command in background from Python Description: This query could focus on executing a shell command from Python and leaving it running in the background.

    import subprocess

subprocess.Popen(["your_shell_command_here"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL, close_fds=True, shell=True)

    By passing shell=True, this code allows the execution of shell commands directly, enabling background execution.

  9. Start long-running process in Python Description: Users may want to start a process in Python that continues running independently for an extended period.

    import subprocess

subprocess.Popen(["your_command_here"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL, close_fds=True)

    Using subprocess.Popen() with appropriate redirections and settings launches the process independently, suitable for long-running tasks.

  10. Python execute command in background Description: This query may seek ways to execute a command from Python and let it run in the background.

    import subprocess

subprocess.Popen(["your_command_here"], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, stdin=subprocess.DEVNULL, close_fds=True)

    By using subprocess.Popen(), the specified command runs independently, detached from the parent process, and continues execution in the background.

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