updating materials from final article

Author: iansedano

subprocess/README.md

@@ -1,3 +1,5 @@
 # Python `subprocess` Examples
 
-Here are the examples for the Real Python article on the `subprocess` module.
+Here are supporting materials for the Real Python tutorial, [The `subprocess` Module: Wrapping Programs With Python](https://realpython.com/python-subprocess/).
+
+Be aware that some examples are designed for particular operating systems. The `basics_unix.py` file won't work on Windows, for instance.

subprocess/choice_react_popen_read_write.py

@@ -0,0 +1,44 @@
+from argparse import ArgumentParser
+from pathlib import Path
+import subprocess
+
+
+def create_new_project(name):
+    project_folder = Path.cwd().absolute() / name
+    project_folder.mkdir()
+    (project_folder / "README.md").touch()
+    with open(project_folder / ".gitignore", mode="w") as f:
+        f.write("\n".join(["venv", "__pycache__"]))
+    commands = [
+        [
+            "python",
+            "-m",
+            "venv",
+            f"{project_folder}/venv",
+        ],
+        ["git", "-C", project_folder, "init"],
+        ["git", "-C", project_folder, "add", "."],
+        ["git", "-C", project_folder, "commit", "-m", "Initial commit"],
+    ]
+    for command in commands:
+        try:
+            subprocess.run(command, check=True, timeout=60)
+        except FileNotFoundError as exc:
+            print(
+                f"Command {command} failed because the process "
+                f"could not be found.\n{exc}"
+            )
+        except subprocess.CalledProcessError as exc:
+            print(
+                f"Command {command} failed because the process "
+                f"did not return a successful return code.\n{exc}"
+            )
+        except subprocess.TimeoutExpired as exc:
+            print(f"Command {command} timed out.\n {exc}")
+
+
+if __name__ == "__main__":
+    parser = ArgumentParser()
+    parser.add_argument("project_name", type=str)
+    args = parser.parse_args()
+    create_new_project(args.project_name)

subprocess/combining_processes.py

@@ -1,6 +1,6 @@
 import sys
 
 try:
-    sys.exit(sys.argv[1])
-except IndexError:
-    sys.exit(0)
+    raise SystemExit(sys.argv[1])
+except IndexError as e:
+    raise SystemExit(0) from e

subprocess/create_new_project.py

@@ -1,41 +1,14 @@
 import subprocess
 
-try:
-    _ = subprocess.run(
-        ["python", "custom_exit.py", "1"], check=True, capture_output=True
-    )
-except subprocess.CalledProcessError as exc:
-    print(exc)
-
-
-failed_process = subprocess.run(
-    ["python", "custom_exit.py", "1"], capture_output=True
-)
 
 try:
-    failed_process.check_returncode()
+    subprocess.run(["python", "timer.py", "5"], timeout=10)
+except FileNotFoundError as exc:
+    print(f"Process failed because the executable could not be found.\n{exc}")
 except subprocess.CalledProcessError as exc:
-    print(exc)
-
-
-try:
-    _ = subprocess.run(
-        ["python", "timer.py", "5"], capture_output=True, timeout=1
+    print(
+        f"Process failed because did not return a successful return code. "
+        f"Returned {exc.returncode}\n{exc}"
     )
 except subprocess.TimeoutExpired as exc:
-    print(exc)
-
-
-try:
-    _ = subprocess.run(["non_existent_program"])
-except FileNotFoundError as exc:  # Subclass of OSError
-    print(exc)
-
-
-try:
-    _ = subprocess.run(
-        ["python", "non_existent_file"], check=True, capture_output=True
-    )
-except subprocess.CalledProcessError as exc:
-    if exc.returncode == 2:
-        print("Python couldn't find the file")
+    print(f"Process timed out.\n{exc}")

subprocess/create_project.py

@@ -0,0 +1,9 @@
+import subprocess
+
+ls_process = subprocess.Popen(["ls", "/usr/bin"], stdout=subprocess.PIPE)
+grep_process = subprocess.Popen(
+    ["grep", "python"], stdin=ls_process.stdout, stdout=subprocess.PIPE
+)
+
+for line in grep_process.stdout:
+    print(line.decode("utf-8").strip())

subprocess/custom_exit.py

@@ -0,0 +1,16 @@
+import subprocess
+from time import sleep
+
+with subprocess.Popen(
+    ["python", "timer.py", "5"], stdout=subprocess.PIPE
+) as process:
+
+    def poll_and_read():
+        print(f"Output from poll: {process.poll()}")
+        print(f"Output from stdout: {process.stdout.read1().decode('utf-8')}")
+
+    poll_and_read()
+    sleep(3)
+    poll_and_read()
+    sleep(3)
+    poll_and_read()

subprocess/error_handling.py

@@ -1,4 +1,4 @@
-from time import sleep, perf_counter
+from time import perf_counter, sleep
 from random import random
 
 print("Press enter to play")
@@ -9,4 +9,4 @@
 start = perf_counter()
 input()
 end = perf_counter()
-print(f"You reacted in {end - start} seconds!\nGoodbye!")
+print(f"You reacted in {(end - start) * 1000:.0f} milliseconds!\nGoodbye!")