updated notes

src/rhcsa.md

@@ -302,17 +302,58 @@ nano myscript.sh
 ```bash
 #!/bin/bash
 echo "Hello, World!"
+
+### Variables ###
+myvar="Hello, World!"
+echo $myvar
+
+### Conditionals ###
+if [ -f /etc/passwd ]; then
+    echo "File exists"
+else
+    echo "File does not exist"
+fi
 ```
 
+### Script to create a directory
+> NOTE: When creating bash scripts you can use particular operators to check for the existence of a file (-f) or directory (-d). The 
+> following example uses the -d operator to check for the existence of a directory. Using conditional logic, if the script detects 
+> that the directory does not exist, the script will go ahead and create it.
 
+```bash
+#!/bin/bash
 
+# Ask the user to enter a directory name
+echo "Enter a directory name: "
 
+# Read the user's input 
+read user_dir
 
+# Check if the user_dir exists
+if [ -d "$user_dir" ]; then
+  echo "The directory '$user_dir' already exists."
+else
+  # Create the user_dir directory if it doesn't exist
+  mkdir "$user_dir"
+  echo "The directory '$user_dir' has been created."
+fi
+```
 
+> In a similar vein, you can check for the existence of a regular file using the -f operator.
 
+```bash
+#!/bin/bash
 
+# Ask the user to enter a filename
+echo "Enter a filename: "
 
+# Read the user's input
+read user_file
 
-
+# Check if the file exists
-
+if [ -f "$user_file" ]; then
-
+  echo "The file '$user_file' exists."
+else
+  echo "The file '$user_file' does not exist."
+fi
+```