diff --git a/sh/tests/master-the-ls/folder1/1 b/sh/tests/master-the-ls/folder1/1
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/2 b/sh/tests/master-the-ls/folder1/2
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/3 b/sh/tests/master-the-ls/folder1/3
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/4 b/sh/tests/master-the-ls/folder1/4
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/5 b/sh/tests/master-the-ls/folder1/5
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/6 b/sh/tests/master-the-ls/folder1/6
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/7 b/sh/tests/master-the-ls/folder1/7
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/8 b/sh/tests/master-the-ls/folder1/8
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder1/9 b/sh/tests/master-the-ls/folder1/9
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/a b/sh/tests/master-the-ls/folder2/a
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/b b/sh/tests/master-the-ls/folder2/b
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/c b/sh/tests/master-the-ls/folder2/c
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/d b/sh/tests/master-the-ls/folder2/d
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/e b/sh/tests/master-the-ls/folder2/e
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/f b/sh/tests/master-the-ls/folder2/f
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/g b/sh/tests/master-the-ls/folder2/g
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/h b/sh/tests/master-the-ls/folder2/h
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/i b/sh/tests/master-the-ls/folder2/i
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls/folder2/j b/sh/tests/master-the-ls/folder2/j
new file mode 100644
index 00000000..e69de29b
diff --git a/sh/tests/master-the-ls_test.sh b/sh/tests/master-the-ls_test.sh
index a4db521a..088cd52d 100755
--- a/sh/tests/master-the-ls_test.sh
+++ b/sh/tests/master-the-ls_test.sh
@@ -14,5 +14,5 @@ challenge() {
     diff <(echo "$submitted") <(echo "$expected")
 }
 
-challenge cl-camp1/folder1
-challenge cl-camp1/folder2
+challenge master-the-ls/folder1
+challenge master-the-ls/folder2
diff --git a/subjects/devops/master-the-ls/README.md b/subjects/devops/master-the-ls/README.md
index cd353b67..51f9c3bf 100644
--- a/subjects/devops/master-the-ls/README.md
+++ b/subjects/devops/master-the-ls/README.md
@@ -19,9 +19,28 @@ Here are some Commands that can help you:
   - Replace all occurrences of a character in a file, and print the result:
     `tr {{find_character}} {{replace_character}} < {{filename}}`
 
+```console
+$ cat uid.txt
+My
+UID
+is
+1000
+$ tr "\n" " " < uid.txt
+My UID is 1000
+$
+```
+
 - `ls`. List directory contents.
 - `sed`. Edit text in a scriptable manner.
 
+```console
+$ cat text.txt
+unix is a great os. unix is opensource. unix is a free os.
+$ sed 's/unix/linux/' text.txt
+linux is a great os. unix is opensource. unix is a free os.
+$
+```
+
 > You have to use Man or Google to know more about commands flags, in order to solve this exercise!
 > Google and Man will be your friends!