Python is a full-on programming language. Its REPL is a REPL for that language. Interacting with the OS and filesystem is a niche, tucked away in a corner of the language.

It has has none of the ergonomic affordances needed to be the user interface for interacting with files and processes.

Here are some simple commands:

    ls
    cd foo
    ls
    rm bar
    cd ../baz
    rm bar
    echo >readme.txt baz directory
    curl -s http://example.com >download

    python
    >>> ls
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    NameError: name 'ls' is not defined
    >>> import system
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ModuleNotFoundError: No module named 'system'
    >>> import os
    >>> os.dir.list()
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: module 'os' has no attribute 'dir'
    >>> help(os)

    >>> os.listdir()
    ['foo', 'bar', 'baz']
    >>> cd foo
      File "<stdin>", line 1
        cd foo
           ^
    SyntaxError: invalid syntax
    >>> chdir("foo")
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    NameError: name 'chdir' is not defined
    >>> os.chdir("foo")
    >>> os.listdir()
    ['bar']
    >>> os.delete("bar")
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: module 'os' has no attribute 'delete'
    >>> os.remove("bar")
    >>> os.chdir("../baz")
    >>> os.remove("bar")
    >>> f = open("readme.txt", "w")
    >>> f.write("baz directory")
    13
    >>> f.close()
    >>> import process
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ModuleNotFoundError: No module named 'process'
    >>> import subprocess
    >>> subprocess.run("curl", "-s", "http://example.com/")
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/usr/lib/python3.9/subprocess.py", line 505, in run
        with Popen(*popenargs, **kwargs) as process:
      File "/usr/lib/python3.9/subprocess.py", line 778, in __init__
        raise TypeError("bufsize must be an integer")
    TypeError: bufsize must be an integer
    >>> subprocess.run(["curl", "-s", "http://example.com/"])
    ...
    CompletedProcess(args=['curl', '-s', 'http://example.com/'], returncode=0)
    >>> subprocess.run(args=["curl", "-s", "http://example.com/"], capture_output=True)
    CompletedProcess(args=['curl', '-s', 'http://example.com/'], returncode=0, stdout=b'...\n', stderr=b'')
    >>> p = subprocess.run(args=["curl", "-s", "http://example.com/"], capture_output=True)
    >>> fh = open("download", "w")
    >>> fh.write(p.stdout)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    TypeError: write() argument must be str, not bytes
    >>> fh = open("download", "wb")
    >>> fh.write(p.stdout)
    559
    >>> fh.close()