diff --git a/src/rtl_manifest/rtl_manifest.py b/src/rtl_manifest/rtl_manifest.py
index 7a0aa44..beb5faf 100644
--- a/src/rtl_manifest/rtl_manifest.py
+++ b/src/rtl_manifest/rtl_manifest.py
@@ -1,4 +1,39 @@
 
+import argparse
+from typing import List
+import pathlib
+
+
 def rtl_manifest_main():
-    print("Hello, world!")
-    pass
\ No newline at end of file
+    parser = argparse.ArgumentParser(
+                    prog='rtl-manifest',
+                    description='Read in sources.list files and return a string of all source files',
+                    epilog='Made by Byron Lathi')
+
+    parser.add_argument("source")
+
+    args = parser.parse_args()
+    files = read_sources(args.source)
+
+    for file in files:
+        print(file, end = " ")
+
+    pass
+
+def read_sources(source_file: str) -> List[str]:
+    files = []
+    base_dir = pathlib.Path(source_file).parent
+
+
+    with open(source_file, "r") as file:
+        for line in file:
+            path = line.strip()
+            if (path.endswith("sources.list")):
+                new_path = pathlib.Path(base_dir) / path
+                for recursive_path in read_sources(new_path):
+                    files.append(recursive_path)
+            else:
+                abs_path = pathlib.Path(base_dir / path).absolute()
+                files.append(str(abs_path))
+
+    return files
\ No newline at end of file
diff --git a/test/sources.list b/test/sources.list
new file mode 100644
index 0000000..5b512af
--- /dev/null
+++ b/test/sources.list
@@ -0,0 +1,2 @@
+src/sub/submodule/sources.list
+src/example.sv
diff --git a/test/src/example.sv b/test/src/example.sv
new file mode 100644
index 0000000..e69de29
diff --git a/test/src/sub/submodule/other_submodule.sv b/test/src/sub/submodule/other_submodule.sv
new file mode 100644
index 0000000..e69de29
diff --git a/test/src/sub/submodule/sources.list b/test/src/sub/submodule/sources.list
new file mode 100644
index 0000000..ae7c5df
--- /dev/null
+++ b/test/src/sub/submodule/sources.list
@@ -0,0 +1,2 @@
+other_submodule.sv
+submodule_regs.rdl
\ No newline at end of file
diff --git a/test/src/sub/submodule/submodule.sv b/test/src/sub/submodule/submodule.sv
new file mode 100644
index 0000000..e69de29
diff --git a/test/src/sub/submodule/submodule_regs.rdl b/test/src/sub/submodule/submodule_regs.rdl
new file mode 100644
index 0000000..e69de29