Ví dụ, bạn có một file `main.py` với:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

Tham số thứ hai cho <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> là giá trị mặc định để trả về.

	public class Downloader extends java.net.Authenticator
	{
	  protected java.net.PasswordAuthentication getPasswordAuthentication()
	  {
	    return new java.net.PasswordAuthentication( System.getenv( "MVNW_USERNAME" ), System.getenv( "MVNW_PASSWORD" ).toCharArray() );
	  }
	  public static void main( String[] args ) throws Exception
	  {
	    setDefault( new Downloader() );

예를 들어 다음과 같은 `main.py` 파일이 있다고 합시다:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | 팁

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 의 두 번째 인자는 반환할 기본값입니다.

여기서는 `"World"`를 넣었기에 기본값으로써 사용됩니다. 넣지 않으면 `None` 이 기본값으로 사용됩니다.

///

 * limitations under the License.
 */
package okhttp3

import okio.Buffer
import okio.Path
import okio.Path.Companion.toPath

val okHttpRoot: Path
  get() = getEnv("OKHTTP_ROOT")!!.toPath()

fun String(vararg codePoints: Int): String {
  val buffer = Buffer()
  for (codePoint in codePoints) {
    buffer.writeUtf8CodePoint(codePoint)
  }
  return buffer.readUtf8()

	c.got = append(c.got, query)
	return c.db.QueryRowContext(ctx, query, args...)
}

func TestConnPoolWrapper(t *testing.T) {
	dialect := os.Getenv("GORM_DIALECT")
	if dialect != "mysql" {
		t.SkipNow()
	}

	dbDSN := os.Getenv("GORM_DSN")
	if dbDSN == "" {
		dbDSN = "gorm:gorm@tcp(localhost:9910)/gorm?charset=utf8&parseTime=True&loc=Local"
	}
	nativeDB, err := sql.Open("mysql", dbDSN)

Например, у вас есть файл `main.py`:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

Второй аргумент <a href=«https://docs.python.org/3.8/library/os.html#os.getenv» class=«external-link» target=«_blank»>`os.getenv()`</a> - это возвращаемое по умолчанию значение.

        Set<Integer> values = new HashSet<>();

        for (Field field : fields) {
            if (field.getType() == int.class) {
                int value = field.getInt(null);
                assertTrue(values.add(value), "Duplicate value found for field: " + field.getName());
            }
        }
    }

    @Test
    @DisplayName("Test constant values follow bit flag pattern")

   *         .call(
   *             () ->
   *                 new UsageHistory(
   *                     username,
   *                     Futures.getDone(loginDateFuture),
   *                     Futures.getDone(recentCommandsFuture)),
   *             executor);
   * }
   *
   * @since 20.0
   */
  @GwtCompatible
  public static final class FutureCombiner<V extends @Nullable Object> {

                    assertThat(peeker.getDone(input1)).isSameInstanceAs("value1");
                    try {
                      peeker.getDone(input2Failed);
                      fail("Peeker.getDone() should fail for failed inputs");
                    } catch (ExecutionException expected) {
                    }
                    try {
                      peeker.getDone(nonInput);

    fi
fi

if [ "$REMOVE_USER_AND_GROUP" = "true" ]; then
    if id "$FESS_USER" > /dev/null 2>&1 ; then
        userdel "$FESS_USER"
    fi

    if getent group "$FESS_GROUP" > /dev/null 2>&1 ; then
        groupdel "$FESS_GROUP"
    fi
fi