diff --git a/python3/10_Modules/06_subprocess/00_subprocess_ex.py b/python3/10_Modules/06_subprocess/00_subprocess_ex.py
index e18be429..11ade470 100644
--- a/python3/10_Modules/06_subprocess/00_subprocess_ex.py
+++ b/python3/10_Modules/06_subprocess/00_subprocess_ex.py
@@ -14,7 +14,7 @@ def execute_command(cmd):
 
 def get_execution_result(cmd):
     p = subprocess.Popen(
-        cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
+        cmd, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE
     )
     output, err = p.communicate()
 
diff --git a/python3/10_Modules/06_subprocess/01_subprocess_ex.py b/python3/10_Modules/06_subprocess/01_subprocess_ex.py
index 8051525c..d6d84b3d 100644
--- a/python3/10_Modules/06_subprocess/01_subprocess_ex.py
+++ b/python3/10_Modules/06_subprocess/01_subprocess_ex.py
@@ -10,8 +10,8 @@
 if sys.platform in ("linux", "linux2", "darwin"):
     cmd = "ifconfig"
     os.system(cmd)
-    subprocess.call(cmd, shell=True)
-    myprocess = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
+    subprocess.call(cmd, shell=False)
+    myprocess = subprocess.Popen(cmd, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
     output, err = myprocess.communicate()
     print("output==============\n", output)
     print("err=================\n", err)
diff --git a/python3/10_Modules/06_subprocess/02_subprocess_ex.py b/python3/10_Modules/06_subprocess/02_subprocess_ex.py
index ebafd2af..c0dd49f4 100644
--- a/python3/10_Modules/06_subprocess/02_subprocess_ex.py
+++ b/python3/10_Modules/06_subprocess/02_subprocess_ex.py
@@ -2,9 +2,9 @@
 import sys
 
 if sys.platform == "win32":
-    subprocess.call(["dir", "/x"], shell=True)
+    subprocess.call(["dir", "/x"], shell=False)
 else:
-    subprocess.call(["ls", "-1"], shell=True)
+    subprocess.call(["ls", "-1"], shell=False)
 
 # Command with shell expansion
 if sys.platform == "win32":
diff --git a/python3/10_Modules/06_subprocess/cleanup_pid.py b/python3/10_Modules/06_subprocess/cleanup_pid.py
index bee2b800..5370942d 100644
--- a/python3/10_Modules/06_subprocess/cleanup_pid.py
+++ b/python3/10_Modules/06_subprocess/cleanup_pid.py
@@ -21,7 +21,7 @@ def check_pid(pid):
 def get_elapsed_time(pid):
     """get the elapsed time of the process with this pid"""
     cmd = f"ps -p {str(pid)} -o pid,etime"
-    proc = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
+    proc = subprocess.Popen(cmd, shell=False, stdout=subprocess.PIPE)
     # get data from stdout
     proc.wait()
     results = proc.stdout.readlines()
diff --git a/python3/11_File_Operations/05_pdf_files/a_create_pdfs/c_report_generation_in_required_format.py b/python3/11_File_Operations/05_pdf_files/a_create_pdfs/c_report_generation_in_required_format.py
index fe2ab6a6..32b8d30d 100644
--- a/python3/11_File_Operations/05_pdf_files/a_create_pdfs/c_report_generation_in_required_format.py
+++ b/python3/11_File_Operations/05_pdf_files/a_create_pdfs/c_report_generation_in_required_format.py
@@ -109,8 +109,7 @@ def __init__(self):
             process = subprocess.Popen(
                 [path_to_pdf],
                 bufsize=2048,
-                shell=True,
-                stdin=subprocess.PIPE,
+                shell=False, stdin=subprocess.PIPE,
                 stdout=subprocess.PIPE,
             )
             process.wait()