python · pohlt · Oct 26, 2021 · Oct 26, 2021 · Oct 26, 2021 · Oct 27, 2021
diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
@@ -1354,6 +1354,23 @@ The following example uses no proxies at all, overriding environment settings::
    ...     f.read().decode('utf-8')
    ...
 
+.. _urllib-request-cli:
+
+:mod:`urllib.request` can also be invoked directly using the :option:`-m`
+switch of the interpreter with an ``URL`` argument::
+
+        python -m urllib.request https://python.org/
+
+By default, the downloaded data is printed to stdout.  The option ``-o/--output``
+specifies an output file where the downloaded data is stored instead of being
+printed::
+
+        python -m urllib.request https://python.org/ --output python.html
+
+If the output file already exists, its content is overwritten.
+
+.. versionadded:: 3.11
+
 
 Legacy interface
 ----------------

diff --git a/Lib/test/test_urllib2_localnet.py b/Lib/test/test_urllib2_localnet.py
@@ -7,6 +7,9 @@
 import threading
 import unittest
 import hashlib
+import subprocess
+import sys
+import tempfile
 
 from test.support import hashlib_helper
 from test.support import threading_helper
@@ -660,6 +663,38 @@ def test_line_iteration(self):
                              (index, len(lines[index]), len(line)))
         self.assertEqual(index + 1, len(lines))
 
+    def test_download_to_stdout(self):
+        content = b"My hovercraft is full of eels."
+        handler = self.start_server([(200, [], content)])
+        proc = subprocess.run(
+            [sys.executable, "-m", "urllib.request",
+            f"http://localhost:{handler.port}"],
+            capture_output=True
+        )
+        self.assertEqual(proc.stdout, content)
+        self.assertEqual(proc.stderr, b"")
+
+    def test_download_to_file(self):
+        content = b"I will not buy this record; it is scratched."
+        handler = self.start_server([(200, [], content)]*2)
+
+        with tempfile.TemporaryDirectory() as directory:
+            for option in ["--output", "-o"]:
+                filename = os.path.join(
+                    directory, f"download-test{option}.txt"
+                )
+                proc = subprocess.run(
+                    [sys.executable, "-m", "urllib.request",
+                    f"http://localhost:{handler.port}",
+                    option, filename],
+                    capture_output=True
+                )
+                with open(filename, "rb") as f:
+                    file_content = f.read()
+                self.assertEqual(proc.stdout, b"")
+                self.assertEqual(proc.stderr, b"")
+                self.assertEqual(file_content, content)
+
 
 def setUpModule():
     thread_info = threading_helper.threading_setup()

diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
@@ -2781,3 +2781,36 @@ def proxy_bypass(host):
     # By default use environment variables
     getproxies = getproxies_environment
     proxy_bypass = proxy_bypass_environment
+
+
+def _download():
+    import argparse
+
+    parser = argparse.ArgumentParser(
+        description="Download the provided URL (FTP/HTTP/HTTPS supported) "
+        "and print it to stdout by default. If specified, write to OUTPUT "
+        "instead."
+    )
+    parser.add_argument("URL", help="(encoded) URL to download")
+    parser.add_argument(
+        "-o",
+        "--output",
+        type=argparse.FileType('wb'), default=sys.stdout.buffer,
+        help="write to OUTPUT instead of stdout"
+    )
+    args = parser.parse_args()
+
+    buffer = memoryview(bytearray(32768))
+    try:
+        with urlopen(args.URL) as response:
+            while n_bytes_read := response.readinto(buffer):
+                args.output.write(buffer[:n_bytes_read])
+    except URLError as exc:
+        print(f"Error while downloading '{args.URL}': {exc.reason}")
+
+    if args.output is not sys.stdout.buffer:
+        args.output.close()
+
+
+if __name__ == "__main__":
+    _download()
diff --git a/Misc/ACKS b/Misc/ACKS
@@ -76,6 +76,7 @@ Jason Asbahr
 David Ascher
 Ammar Askar
 Neil Aspinall
+Peter Åstrand
 Chris AtLee
 Aymeric Augustin
 Andres Ayala
@@ -491,6 +492,7 @@ Daniel Ellis
 Phil Elson
 David Ely
 Victor van den Elzen
+Vlad Emelianov
 Jeff Epler
 Tom Epperly
 Gökcen Eraslan
@@ -1384,6 +1386,7 @@ Jean-François Piéronne
 Oleg Plakhotnyuk
 Anatoliy Platonov
 Marcel Plch
+Thomas Pohl
 Remi Pointel
 Jon Poler
 Ariel Poliak
@@ -1998,8 +2001,5 @@ Tarek Ziadé
 Jelle Zijlstra
 Gennadiy Zlobin
 Doug Zongker
-Peter Åstrand
-Vlad Emelianov
-Andrey Doroschenko
 
 (Entries should be added in rough alphabetical order by last names)
diff --git a/Misc/NEWS.d/next/Library/2021-10-26-07-02-51.bpo-45466.DOzSv2.rst b/Misc/NEWS.d/next/Library/2021-10-26-07-02-51.bpo-45466.DOzSv2.rst
@@ -0,0 +1,3 @@
+The :mod:`urllib.request` module can now download files (e.g.
+``python -m urllib.request https://python.org/``). For more
+info, see ``python -m urllib.request -h``. Patch by Thomas Pohl.