对于使用Windows映像来运行操作的人，有几个要点需要了解:

假设GitHub动作使用CMD shell是不正确的。他们默认使用PowerShell。 您可以指定shell使用以下方式:

- run: |
    ...
  shell: cmd

您可以使用值'bash'在bash shell上下文中执行命令。

所以，总而言之，你不需要浪费潜在的时间试图弄清楚如何以破旧的cmd方式做事(就像我做的那样)。

为了简单地获取当前分支的名称，你可以在将shell设置为'bash'时使用流行的解决方案，或者使用例如下面的简单方法在默认PowerShell中设置变量:

$branchName = $Env:GITHUB_REF -replace "refs/heads/", ""

现在$ {{github。Ref}}是获取分支名称的正确方法。 请记住${{github。Ref}}有refs/heads/..前缀

我相信GITHUB_REF是唯一包含分支名称的环境变量。

你可以从字符串的其余部分提取分支名称，如下所示:

${GITHUB_REF##*/}

例子:

$ GITHUB_REF=refs/heads/feature-branch-1
$ echo ${GITHUB_REF##*/}
feature-branch-1

更新:添加了一个完整的工作流示例。

工作流

name: CI
on: push
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Git checkout
        uses: actions/checkout@v1
      - name: Branch name
        run: echo running on branch ${GITHUB_REF##*/}
      - name: Build
        run: docker build -t tedmiston/tag-example:${GITHUB_REF##*/} .

来源:https://github.com/tedmiston/x/blob/master/.github/workflows/workflow.yml

示例输出-主分支

Run docker build -t tedmiston/tag-example:${GITHUB_REF##*/} .
  docker build -t tedmiston/tag-example:${GITHUB_REF##*/} .
  shell: /bin/bash -e {0}
Sending build context to Docker daemon  146.9kB

Step 1/1 : FROM alpine
latest: Pulling from library/alpine
9d48c3bd43c5: Pulling fs layer
9d48c3bd43c5: Verifying Checksum
9d48c3bd43c5: Download complete
9d48c3bd43c5: Pull complete
Digest: sha256:72c42ed48c3a2db31b7dafe17d275b634664a708d901ec9fd57b1529280f01fb
Status: Downloaded newer image for alpine:latest
 ---> 961769676411
Successfully built 961769676411
Successfully tagged tedmiston/tag-example:master

日志:https://github.com/tedmiston/x/commit/cdcc58a908e41d3d90c39ab3bf6fef1ad2c4238a/checks一步:16

示例输出-非主分支

Run docker build -t tedmiston/tag-example:${GITHUB_REF##*/} .
  docker build -t tedmiston/tag-example:${GITHUB_REF##*/} .
  shell: /bin/bash -e {0}
Sending build context to Docker daemon  144.9kB

Step 1/1 : FROM alpine
latest: Pulling from library/alpine
9d48c3bd43c5: Pulling fs layer
9d48c3bd43c5: Verifying Checksum
9d48c3bd43c5: Download complete
9d48c3bd43c5: Pull complete
Digest: sha256:72c42ed48c3a2db31b7dafe17d275b634664a708d901ec9fd57b1529280f01fb
Status: Downloaded newer image for alpine:latest
 ---> 961769676411
Successfully built 961769676411
Successfully tagged tedmiston/tag-example:branch-name-test

日志:https://github.com/tedmiston/x/commit/4e8d31259f861aaa2c30375756fc081c3659bddf/checks一步:16

有关参数展开语法的更多信息，请参阅这个答案。

作为参考，GitHub Actions的虚拟环境页面列出了执行环境中可用的所有环境变量。

下面是一个适用于push和pull_request事件的完整工作流

name: whichBranch
on: [pull_request, push]

jobs:
  which_branch:
    runs-on: ubuntu-latest
    steps:
      - name: Extract branch name on push
        if: github.event_name != 'pull_request'
        shell: bash
        run: echo "::set-env name=BRANCH_NAME::$(echo ${GITHUB_REF#refs/heads/})"
        id: extract_branch

      - name: Extract branch name on pull request
        if: github.event_name == 'pull_request'
        run: echo "::set-env name=BRANCH_NAME::$(echo ${GITHUB_HEAD_REF})"

      - name: Print branch name
        run: echo 'The branch name is' $BRANCH_NAME

如果你使用的是V2的actions/checkout，那么你总是可以运行git branch——show-current来获取当前签出的分支的名称。

获取当前分支很简单，下面的代码适用于我和

github.ref_name

是用于获取分支名称的预定义变量吗

jobs:
  main-branch-build:
    if: github.ref_name == 'main'
    runs-on: ubuntu-latest
    steps:
      - name: Check out code
        uses: actions/checkout@v3
  feature-branch-build:
    if: github.ref_name != 'main'
    runs-on: ubuntu-latest
    steps:
    - name: Check out code
      uses: actions/checkout@v3