deno upgrade 命令用来升级 Deno 的版本。
概述
详细命令介绍为：
$ deno upgrade -h
deno-upgrade
Upgrade deno executable to the given version.
Defaults to latest.
The version is downloaded from
https://github.com/denoland/deno/releases
and is used to replace the current executable.
USAGE:
deno upgrade [OPTIONS]
OPTIONS:
--dry-run Perform all checks without replacing old exe
-f, --force Replace current exe even if not out-of-date
-h, --help Prints help information
-L, --log-level <log-level> Set log level [possible values: debug, info]
-q, --quiet Suppress diagnostic output
--version <version> The version to upgrade to
默认会升级到 Deno 的最新版本。
此命令会从 https://github.com/denoland/deno/releases 获取最新版本，并替换到当前版本。
命令行参数
--dry-run
尝试升级，但不是真正的升级，只是做了一些升级需要的检查。
如果当前不是最新版，则会升级到最新版。
$ deno upgrade --dry-run
Checking for latest version
Version has been found
Deno is upgrading to version 1.0.5
downloading https://github.com/denoland/deno/releases/download/v1.0.5/deno-x86_64-apple-darwin.zip
downloading https://github-production-release-asset-2e65be.s3.amazonaws.com/133442384/6d099280-a5bc-11ea-8293-3999a307e39a?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20200611%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20200611T061000Z&X-Amz-Expires=300&X-Amz-Signature=def71e38584bf02e3558a93265ce160105d857c23bbab4301328076129eedef4&X-Amz-SignedHeaders=host&actor_id=0&repo_id=133442384&response-content-disposition=attachment%3B%20filename%3Ddeno-x86_64-apple-darwin.zip&response-content-type=application%2Foctet-stream
Archive: /var/folders/r1/nrr55q9j51v7h3tkk3y4dmf80000gn/T/.tmpUWFyGR/deno.zip
inflating: deno
Upgrade done successfully
如果当前版本已经是最新版本，则输出：
$ deno upgrade --dry-run
Checking for latest version
Local deno version 1.0.5 is the most recent release
如果升级到一个不存在的版本，则会提示错误：
$ deno upgrade --dry-run --version 2.0.0
Version has been found
Deno is upgrading to version 2.0.0
downloading https://github.com/denoland/deno/releases/download/v2.0.0/deno-x86_64-apple-darwin.zip
error: Import 'https://github.com/denoland/deno/releases/download/v2.0.0/deno-x86_64-apple-darwin.zip' failed: 404 Not Found
注：关于 --version 参数下面有解释。
--force
强制升级，即使当前版本已经已经是最新版。
使用 --force 参数时，Deno 会忽略对于版本的检查。
$ deno upgrade --force
Checking for latest version
Version has been found
Deno is upgrading to version 1.0.5
downloading https://github.com/denoland/deno/releases/download/v1.0.5/deno-x86_64-apple-darwin.zip
downloading https://github-production-release-asset-2e65be.s3.amazonaws.com/133442384/6d099280-a5bc-11ea-8293-3999a307e39a?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20200611%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20200611T061213Z&X-Amz-Expires=300&X-Amz-Signature=7983a542595a1aea53fc355f4c378c911752158be8f8e0e0391e72b0aa1bf39c&X-Amz-SignedHeaders=host&actor_id=0&repo_id=133442384&response-content-disposition=attachment%3B%20filename%3Ddeno-x86_64-apple-darwin.zip&response-content-type=application%2Foctet-stream
Archive: /var/folders/r1/nrr55q9j51v7h3tkk3y4dmf80000gn/T/.tmpWCYuzY/deno.zip
inflating: deno
Upgrade done successfully
--version
升级到特定版本。
此参数使用语义化版本，如果不是，则抛出错误，并停止升级。
$ deno upgrade --version 2.0
Invalid semver passed
此命令名虽然是 upgrade，但是不仅仅可以升级，也可以降级。