piping and errors

Author: iansedano

subprocess/combining_processes.py

@@ -0,0 +1,31 @@
+import subprocess
+
+# Variations to do the same thing
+
+ls_process = subprocess.run(["ls"], capture_output=True)
+grep_process = subprocess.run(["grep", "basics"], input=ls_process.stdout)
+
+subprocess.run(
+    ["grep", "basics"],
+    input=subprocess.run(["ls"], capture_output=True).stdout,
+)
+
+ls_process = subprocess.run(["ls"], stdout=subprocess.PIPE)
+grep_process = subprocess.run(["grep", "basics"], stdin=ls_process.stdout)
+
+# This one doesn't work
+print(subprocess.PIPE)  # -1
+ls_process = subprocess.run(["ls"], stdout=-1)
+print(ls_process.stdout)  # Successfully outputs
+grep_process = subprocess.run(
+    ["grep", "basics"], stdin=ls_process.stdout  # Why does this not work??
+)
+
+piped_process = subprocess.run(["bash", "-c", "ls | grep basic"])
+
+
+with open("buffer", "w") as buffer:
+    ls_process = subprocess.run(["ls"], stdout=buffer)
+
+with open("buffer", "r") as buffer:
+    grep_process = subprocess.run(["grep", "basic"], stdin=buffer)

subprocess/custom_exit.py

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

subprocess/error_handling.py

@@ -0,0 +1,41 @@
+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()
+except subprocess.CalledProcessError as exc:
+    print(exc)
+
+
+try:
+    _ = subprocess.run(
+        ["python", "timer.py", "5"], capture_output=True, timeout=1
+    )
+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")