avoid freeze when capturing external stderr (#6700)

* avoid freeze when capturing external stderr

* try replace from sh to bash

* change description

* fmt code

crates/nu-command/tests/commands/do_.rs

@@ -59,3 +59,68 @@ fn do_with_semicolon_break_on_failed_external() {
 
     assert_eq!(actual.out, "");
 }
+
+#[test]
+#[cfg(not(windows))]
+fn ignore_error_not_hang_nushell() {
+    use nu_test_support::fs::Stub::FileWithContent;
+    use nu_test_support::pipeline;
+    use nu_test_support::playground::Playground;
+    Playground::setup("external with many stderr message", |dirs, sandbox| {
+        let bytes: usize = 81920;
+        let mut large_file_body = String::with_capacity(bytes);
+        for _ in 0..bytes {
+            large_file_body.push_str("a");
+        }
+        sandbox.with_files(vec![FileWithContent("a_large_file.txt", &large_file_body)]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                do -i {sh -c "cat a_large_file.txt 1>&2"} | complete | get stderr
+            "#
+        ));
+
+        assert_eq!(actual.out, large_file_body);
+    })
+}
+
+#[test]
+#[cfg(not(windows))]
+fn ignore_error_with_both_stdout_stderr_messages_not_hang_nushell() {
+    use nu_test_support::fs::Stub::FileWithContent;
+    use nu_test_support::playground::Playground;
+    Playground::setup(
+        "external with many stdout and stderr messages",
+        |dirs, sandbox| {
+            let script_body = r#"
+        x=$(printf '=%.0s' {1..40960})
+        echo $x
+        echo $x 1>&2
+        "#;
+            let mut expect_body = String::new();
+            for _ in 0..40960 {
+                expect_body.push_str("=");
+            }
+
+            sandbox.with_files(vec![FileWithContent("test.sh", &script_body)]);
+
+            // check for stdout
+            let actual = nu!(
+                cwd: dirs.test(), pipeline(
+                r#"
+                do -i {bash test.sh} | complete | get stdout | str trim
+            "#
+            ));
+            assert_eq!(actual.out, expect_body);
+            // check for stderr
+            let actual = nu!(
+                cwd: dirs.test(), pipeline(
+                r#"
+                do -i {bash test.sh} | complete | get stderr | str trim
+            "#
+            ));
+            assert_eq!(actual.out, expect_body);
+        },
+    )
+}