Escape some symbols in external args (#1687)

* Escape some symbols in external args

* Don't escape on Windows, which does its own

* fix warning

crates/nu-cli/src/commands/classified/external.rs

@@ -116,7 +116,23 @@ fn run_with_stdin(
     let mut command_args = vec![];
     for arg in command.args.iter() {
         let value = evaluate_baseline_expr(arg, &context.registry, scope)?;
-        command_args.push(value.as_string()?.trim_end_matches('\n').to_string());
+        // Do the cleanup that we need to do on any argument going out:
+        let trimmed_value_string = value.as_string()?.trim_end_matches('\n').to_string();
+
+        let value_string;
+        #[cfg(not(windows))]
+        {
+            value_string = trimmed_value_string
+                .replace('$', "\\$")
+                .replace('"', "\\\"")
+                .to_string()
+        }
+        #[cfg(windows)]
+        {
+            value_string = trimmed_value_string
+        }
+
+        command_args.push(value_string);
     }
 
     let process_args = command_args

tests/shell/pipeline/commands/external.rs

@@ -48,6 +48,20 @@ fn automatically_change_directory_with_trailing_slash_and_same_name_as_command()
     })
 }
 
+// #[test]
+// fn correctly_escape_external_arguments() {
+//     let actual = nu!(cwd: ".", r#"^echo '[{"foo": "bar"}]' | from-json | to-json"#);
+
+//     assert_eq!(actual, "{\"foo\":\"bar\"}");
+// }
+
+#[test]
+fn correctly_escape_external_arguments() {
+    let actual = nu!(cwd: ".", r#"^echo '$0'"#);
+
+    assert_eq!(actual, "$0");
+}
+
 mod it_evaluation {
     use super::nu;
     use nu_test_support::fs::Stub::{EmptyFile, FileWithContent, FileWithContentToBeTrimmed};