如果你已經知道什麼是「環境變數」並且知道如何使用它們，你可以放心跳過這一部分。

///

環境變數（也稱為「**env var**」）是一個獨立於 Python 程式碼**之外**的變數，它存在於**作業系統**中，可以被你的 Python 程式碼（或其他程式）讀取。

環境變數對於處理應用程式**設定**（作為 Python **安裝**的一部分等方面）非常有用。

## 建立和使用環境變數 { #create-and-use-env-vars }

你在 **shell（終端機）**中就可以**建立**和使用環境變數，並不需要用到 Python：

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console
// 你可以使用以下指令建立一個名為 MY_NAME 的環境變數
$ export MY_NAME="Wade Wilson"

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package gradlebuild.binarycompatibility.rules;

import gradlebuild.binarycompatibility.metadata.KotlinMetadataQueries;

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.http2.hpackjson

import com.squareup.moshi.FromJson
import com.squareup.moshi.Moshi
import com.squareup.moshi.ToJson

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.slack;

import java.io.IOException;
import java.io.InterruptedIOException;
import okhttp3.HttpUrl;
import okio.Timeout;

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.collect.ReflectionFreeAssertThrows.assertThrows;
import static com.google.common.truth.Truth.assertThat;

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static java.util.Collections.singleton;

import com.google.common.annotations.GwtCompatible;

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import org.jspecify.annotations.Nullable;

/**

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static java.util.concurrent.TimeUnit.MILLISECONDS;

 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.util.concurrent;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.math;

import static com.google.common.math.MathBenchmarking.ARRAY_MASK;
import static com.google.common.math.MathBenchmarking.ARRAY_SIZE;