diff --git a/src/book/runtime.rs b/src/book/runtime.rs
index 1f9caeb..d9d8486 100644
--- a/src/book/runtime.rs
+++ b/src/book/runtime.rs
@@ -187,21 +187,23 @@ impl<'a> FunctionRef<'a> {
         let command_line = self.function.execution.get_command_line()?;
         let mut env = BTreeMap::new();
 
-        // interpolate the arguments
-        let command_line = {
-            let mut interpolated = Vec::new();
-            for arg in command_line {
-                interpolated.push(if let Some(caps) = ARG_VALUE_PARSER.captures(&arg) {
-                    let var_name = caps
-                        .get(1)
-                        .ok_or(ARG_EXPRESSION_ERROR)
-                        .map_err(|e| anyhow!(e))?
-                        .as_str();
+    // interpolate the arguments
+    let command_line = {
+        let mut interpolated = Vec::new();
+        for arg in command_line {
+            if ARG_VALUE_PARSER.is_match(&arg) {
+                // Process args with placeholders by replacing only the matched     patterns
+                let mut processed_arg = arg.clone();
+
+                // Find all matches and collect the replacements
+                let mut replacements = Vec::new();
+                for caps in ARG_VALUE_PARSER.captures_iter(&arg) {
+                    let full_match = caps.get(0).unwrap().as_str();
+                    let var_name = caps.get(1).ok_or(ARG_EXPRESSION_ERROR).map_err(|    e| anyhow!(e))?.as_str();
                     let var_default = caps.get(3).map(|m| m.as_str());
 
-                    // read variable from the environment if the name starts with env. or ENV.
-                    if var_name.starts_with("env.") || var_name.starts_with("ENV.") {
-                        let env_var_name = var_name.replace("env.", "").replace("ENV.", "");
+                    let replacement = if var_name.starts_with("env.") || var_name.  starts_with("ENV.") {
+                        let env_var_name = var_name.replace("env.", "").replace ("ENV.", "");
                         let env_var = std::env::var(&env_var_name);
                         let env_var_value = if let Ok(value) = env_var {
                             value
@@ -214,12 +216,11 @@ impl<'a> FunctionRef<'a> {
                             ));
                         };
 
-                        // add the environment variable to the command line for later use
+                        // add the environment variable to the command line for     later use
                         env.insert(env_var_name, env_var_value.to_owned());
 
                         env_var_value
                     } else if let Some(value) = arguments.get(var_name) {
-                        // if the value is empty and there's a default value, use the default value
                         if value.is_empty() {
                             if let Some(def) = var_default {
                                 def.to_string()
@@ -227,26 +228,34 @@ impl<'a> FunctionRef<'a> {
                                 value.to_string()
                             }
                         } else {
-                            // otherwise, use the provided value
                             value.to_string()
                         }
                     } else if let Some(default_value) = var_default {
-                        // if the value is not provided and there's a default value, use the default value
                         default_value.to_string()
                     } else {
-                        return Err(anyhow::anyhow!("argument {} not provided", var_name));
-                    }
-                } else {
-                    arg
-                });
-            }
-            interpolated
-        };
+                        return Err(anyhow::anyhow!("argument {} not provided",  var_name));
+                    };
 
-        // final parsing
-        CommandLine::from_vec_with_env(&command_line, env)
+                    replacements.push((full_match, replacement));
+                }
+
+                // Apply all replacements to the arg string
+                for (pattern, replacement) in replacements {
+                    processed_arg = processed_arg.replace(pattern, &replacement);
+                }
+
+                interpolated.push(processed_arg);
+            } else {
+                // For args without placeholders, use as-is
+                interpolated.push(arg);
+            }
+        }
+        interpolated
+    };
+            // final parsing
+            CommandLine::from_vec_with_env(&command_line, env)
+        }
     }
-}
 
 #[cfg(test)]
 mod tests {