How to Change the Current Directory When Using Subprocess?

Changing Current Directory with Subprocess

When executing a script within a subdirectory or superdirectory, it's necessary to navigate to the desired directory first. However, using subprocess to change the working directory may encounter errors. In this article, we'll explore the issue and provide a solution.

The issue arises when attempting to execute the 'cd' command through subprocess, as demonstrated in the example code provided. Subprocess attempts to call 'cd' as a program, while in reality, it's a shell internal command that needs to be called as 'cd '.

To avoid this error, use 'subprocess.call('cd ..', shell=True)' to specify that the command should be executed by the shell. However, this approach is unnecessary because changing the current directory in a child process will not affect the parent process's directory.

Instead, there are alternate methods to achieve the desired functionality:

• os.chdir(): Use this method to directly change the working directory of the parent process. For instance, to execute 'ls' in the root directory:

<code class="python">os.chdir("/")
subprocess.Popen("ls")
os.chdir(wd)</code>

• 'cwd' Parameter: Specify the working directory in the subprocess call itself using the 'cwd' parameter. This will change the working directory before executing the subprocess:

<code class="python">subprocess.Popen("ls", cwd="/")</code>

By employing these methods, you can effectively control the current directory when executing scripts within different directories using subprocess.

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