diff --git a/src/abstract_tree/command.rs b/src/abstract_tree/command.rs
index 98c8034..78b68f2 100644
--- a/src/abstract_tree/command.rs
+++ b/src/abstract_tree/command.rs
@@ -1,4 +1,4 @@
-use std::process;
+use std::process::{self, Stdio};
 
 use serde::{Deserialize, Serialize};
 use tree_sitter::Node as SyntaxNode;
@@ -53,18 +53,19 @@ impl AbstractTree for Command {
     }
 
     fn validate(&self, _source: &str, _context: &Context) -> Result<(), ValidationError> {
-        todo!()
+        Ok(())
     }
 
     fn run(&self, _source: &str, _context: &Context) -> Result<Value, RuntimeError> {
         let output = process::Command::new(&self.command_text)
             .args(&self.command_arguments)
+            .stdout(Stdio::piped())
+            .stderr(Stdio::inherit())
             .spawn()?
             .wait_with_output()?
             .stdout;
-        let string = String::from_utf8(output)?;
 
-        Ok(Value::String(string))
+        Ok(Value::String(String::from_utf8(output)?))
     }
 }
 
diff --git a/tests/commands.rs b/tests/commands.rs
index b6a4bbf..98a462c 100644
--- a/tests/commands.rs
+++ b/tests/commands.rs
@@ -1,20 +1,14 @@
 use dust_lang::{interpret, Value};
 
-use std::fs::{remove_file, write};
-
 #[test]
 fn simple_command() {
-    assert_eq!(interpret("^echo hi"), Ok(Value::String("".to_string())))
+    assert_eq!(interpret("^echo hi"), Ok(Value::String("hi\n".to_string())))
 }
 
 #[test]
 fn assign_command_output() {
-    write("target/test.txt", "123").unwrap();
-
     assert_eq!(
-        interpret("x = ^cat target/test.txt; x"),
-        Ok(Value::String("123".to_string()))
+        interpret("x = ^ls; length(str:lines(x))"),
+        Ok(Value::Integer(11))
     );
-
-    remove_file("target/test.txt").unwrap();
 }
diff --git a/tree-sitter-dust/corpus/commands.txt b/tree-sitter-dust/corpus/commands.txt
index d7da01f..eaa2e9e 100644
--- a/tree-sitter-dust/corpus/commands.txt
+++ b/tree-sitter-dust/corpus/commands.txt
@@ -59,33 +59,6 @@ Command Sequence with Arguments
 
 --------------------------------------------------------------------------------
 
-(root
-  (statement
-    (statement_kind
-      (expression
-        (command
-          (command_text)
-          (command_argument)
-          (command_argument)
-          (command_argument)
-          (command_argument)))))
-  (statement
-    (statement_kind
-      (expression
-        (command
-          (command_text)
-          (command_argument)
-          (command_argument))))))
-
-================================================================================
-Command Sequence with Arguments
-================================================================================
-
-^cargo run -- -c "output('hi there')"
-^ls --long -a
-
---------------------------------------------------------------------------------
-
 (root
   (statement
     (statement_kind
@@ -108,7 +81,7 @@ Command Sequence with Arguments
 Command Assignment
 ================================================================================
 
-ls_output = ^ls --long -a;
+ls_output = ^ls;
 cat_output = ^cat Cargo.toml;
 
 --------------------------------------------------------------------------------
@@ -123,9 +96,7 @@ cat_output = ^cat Cargo.toml;
           (statement_kind
             (expression
               (command
-                (command_text)
-                (command_argument)
-                (command_argument))))))))
+                (command_text))))))))
   (statement
     (statement_kind
       (assignment
@@ -146,32 +117,6 @@ ls_output = ^ls --long -a; ls_output
 
 --------------------------------------------------------------------------------
 
-(root
-  (statement
-    (statement_kind
-      (assignment
-        (identifier)
-        (assignment_operator)
-        (statement
-          (statement_kind
-            (expression
-              (command
-                (command_text)
-                (command_argument)
-                (command_argument))))))))
-  (statement
-    (statement_kind
-      (expression
-        (identifier)))))
-
-================================================================================
-Command with Semicolon
-================================================================================
-
-ls_output = ^ls --long -a; ls_output
-
---------------------------------------------------------------------------------
-
 (root
   (statement
     (statement_kind
diff --git a/tree-sitter-dust/grammar.js b/tree-sitter-dust/grammar.js
index 3b5c906..093986a 100644
--- a/tree-sitter-dust/grammar.js
+++ b/tree-sitter-dust/grammar.js
@@ -101,7 +101,7 @@ module.exports = grammar({
         ),
       ),
 
-    command_text: $ => /\S+/,
+    command_text: $ => /[^\s;]+/,
 
     command_argument: $ =>
       choice(
diff --git a/tree-sitter-dust/src/grammar.json b/tree-sitter-dust/src/grammar.json
index 27e0339..6953c39 100644
--- a/tree-sitter-dust/src/grammar.json
+++ b/tree-sitter-dust/src/grammar.json
@@ -293,7 +293,7 @@
     },
     "command_text": {
       "type": "PATTERN",
-      "value": "\\S+"
+      "value": "[^\\s;]+"
     },
     "command_argument": {
       "type": "CHOICE",
diff --git a/tree-sitter-dust/src/parser.c b/tree-sitter-dust/src/parser.c
index d1cb36b..18f39e3 100644
--- a/tree-sitter-dust/src/parser.c
+++ b/tree-sitter-dust/src/parser.c
@@ -2320,7 +2320,8 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
           lookahead == '\n' ||
           lookahead == '\r' ||
           lookahead == ' ') SKIP(22)
-      if (lookahead != 0) ADVANCE(76);
+      if (lookahead != 0 &&
+          lookahead != ';') ADVANCE(76);
       END_STATE();
     case 23:
       if (lookahead == '&') ADVANCE(154);
@@ -2558,7 +2559,8 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
       if (lookahead == '|') ADVANCE(51);
       if (lookahead == '\t' ||
           lookahead == '\r' ||
-          lookahead == ' ') ADVANCE(41);
+          lookahead == ' ' ||
+          lookahead == ';') ADVANCE(41);
       if (lookahead != 0) ADVANCE(75);
       END_STATE();
     case 52:
@@ -2585,7 +2587,8 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
           lookahead != '\t' &&
           lookahead != '\n' &&
           lookahead != '\r' &&
-          lookahead != ' ') ADVANCE(76);
+          lookahead != ' ' &&
+          lookahead != ';') ADVANCE(76);
       END_STATE();
     case 55:
       ACCEPT_TOKEN(anon_sym_SEMI);
@@ -2736,7 +2739,8 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
       if (lookahead == '|') ADVANCE(51);
       if (lookahead == '\t' ||
           lookahead == '\r' ||
-          lookahead == ' ') ADVANCE(41);
+          lookahead == ' ' ||
+          lookahead == ';') ADVANCE(41);
       if (lookahead != 0) ADVANCE(75);
       END_STATE();
     case 76:
@@ -2745,7 +2749,8 @@ static bool ts_lex(TSLexer *lexer, TSStateId state) {
           lookahead != '\t' &&
           lookahead != '\n' &&
           lookahead != '\r' &&
-          lookahead != ' ') ADVANCE(76);
+          lookahead != ' ' &&
+          lookahead != ';') ADVANCE(76);
       END_STATE();
     case 77:
       ACCEPT_TOKEN(aux_sym_command_argument_token1);