Set-output Truncates Multiline Strings

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I got response from the team. 

% and \n and \r can be escaped like below, the runner will unescape in reverse.


Please try to add next three red lines to your yml, kindly let me know whether this could help.

- shell: bash
        id: release_description
        run: |
          description=$(./resources/ ${{ steps.versioning.outputs.cli_version }})
          echo $description
<font color="#FF0000"> description="${description//'%'/'%25'}"
echo "::set-output name=description::$description"
if: startsWith(steps.commit_message.outputs.commit_message, 'Version change')

 I tested in my side, after adding these lines, I can use echo " ${{ steps.release_description.outputs.description1 }} " to output multiple line value. Please pay attention to “”



Sorry, I just noticed your reply!

Thanks very much for this, it resolves the issue.

It took me an hour to realize that multi-line strings were the issue for me, and then a few more hours to find this solution.

It would be great if multi-line strings as values could be better supported, and documented.

Here are a few observation. First, it is important to suppress word-splitting upon expansion in bash. This is easiest done by enclosing with double quotes:

REPORT="$(cat logfile)"

Similarly, word splitting also has to be suppressed when reading back:

echo "$REPORT"

The double quotes are necessary.

However, Workflows gets confused/truncates when dealing with an expanded multi-line value:

echo "::set-env name=REPORT::$REPORT"

This does not work for multi-line variables.

The solution above uses a standard bash feature to expand and substitute characters:


This essentially makes the value into a single line string.

The github engineers then also knew that when reading back the variable in the workflow these escape values get substituted back to the actual characters:

${{ env.REPORT }}

This results actually in a multi-line string. Unfortunately, this is not documented anywhere and comes across a bit as magic. If there are other substitutions it would be good to also document those.


Thanks so much posting this. I came across the same issue and found this rather obscure solution, after a lot of trial and error.

A couple observation dealing with multiline values, mostly as a reminder on how this works.

If using bash, it is important to suppress word splitting upon parameter expansion, to keep the line breaks. It is easiest with double quotes:

REPORT="$(cat log.out)"

Accessing the variable also invokes word splitting, which needs to be suppressed:

echo "$REPORT"

However, set-output or set-env does not work with expanded multiline values:

echo "::set-env name=REPORT::$REPORT"

This does does not work, as Workflows somehow truncates or ignores the value.

The solution above is to escape the newlines and other apparently unhandled characters using bash expansion and substitution. This makes the value effectively single line.

The thing to notice is that Workflows substitutes the escaped characters back when the parameters is used in ${{ }}:

body: |
  eslint and diff report:
  ${{ env.REPORT }}

Here the final value includes actual newlines.

It would be great if this behaviour cold be documented somewhere. For example, are there other substitutions happening ?

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@andreasplesch  Thank you for your further investigation. I would recommand you to create an issue in the action toolkit repo . You could ask for adding an example for set-env and set-output with multiline values in this document. 

Thanks. Good to know that there is more in depth documentation available in the toolkit repo. I think a link from the main help page at to this documentation could be helpful.

Hm, it looks like newlines should already be escaped automatically:

Anyways, here is the new issue in the repo:

and a related issue:

Escaping of special characters already happened for javascript actions but does not for bash scripts. There is a plan to update documentation.

I have bumped into this exact issue, and found another solution: we can use jq to do the conversion into a valid JSON string for us, and then use fromJSON to unpack it again.

For example: the variable $mystr holds the (multiline) contents of file myfile; we convert to a one-line JSON string with jq --raw-input --slurp '.', and then unpack in a later step.

- id: mystep
  run: |
    mystr=$(< myfile)
    msg=$(printf '%s' "$mystr" | jq --raw-input --slurp '.')
    echo "::set-output name=msg::$msg"

- run: |
    echo "${{ fromJSON(steps.mystep.outputs.msg) }}"

Notice that this isn’t fool-proof, either: if the expanded string contains double quotes, the echo in the second step might get confused.


I also have an issue where I would like to output a list of paths and other data only if the action processes multiple files (to push them to or any nuget feeds).

Here is yet another potential work-around.

This is working in a CI Action job of mine, which takes the content of a text file that contains test results and posts the whole content (which is multiline content) back to the relevant PR as a comment. The resulting comment accurately reflects the original newlines of the test result output.

name: build_for_PR

      - main


    runs-on: ubuntu-18.04

    - uses: actions/checkout@v1

    - name: run_all_linux_ci
      run: ./

    - name: get_legacy_gui_test_output
      id: legacy_out_01
      run: echo "::set-output name=testconfout::$(cat path_from_my_git_root/to/build/artifacts/db_mgr_test_output.txt | python3 -c 'import sys; print("\\","\\\\").replace("\"","\\\"").replace("\n","\\n"))' )\n"

    - uses: actions/github-script@v3
        script: |
          var theContent = "${{join(steps.legacy_out_01.outputs.*, '\n')}}";
          issue_number: context.issue.number,
          owner: context.repo.owner,
          repo: context.repo.repo,
          body: 'LEGACY GUI TEST OUTPUT (from most recent CI job on this PR):\n\n' + theContent

This was inspired by the approach posted by @ bewuethr. As far as I can tell in a couple days of usage, the python-based solution I am sharing does manage to handle double-quotes in the text (in addition to newlines).


Thanks a lot for sharing, this unblocked me :slight_smile:

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For completeness, I want to point out that you can also use an environment variable via environment files for multiline text: Workflow commands for GitHub Actions - GitHub Docs

  - name: Set the value
    shell: bash
    run: |
      curl >> $GITHUB_ENV
      echo 'EOF' >> $GITHUB_ENV
  - name: Print multiline response
    shell: bash
    run: |
      echo "$JSON_RESPONSE"

Might be technically possible, but so far the only working result I could get was from this answer

Has this been fixed? I built a function to work around this, and now it displays the escape sequences.

Here’s my multi-line output solution which requires no changing of the data, however you do have to write it to a text file first.

In this example I’m using it for stderr, but you can adapt it to any kind of multi-line output too

# on windows, powershell fails on stderr output and improperly
# handles putting it in the file. It's required to run as cmd /c
# if not using windows, then change this command appropriately
- name: build
  id: build
  continue-on-error: true
  run: cmd /c "build 2> errors.txt"

- name: Set error-log to var
  uses: actions/github-script@v4
  id: error-log
  if: != 'success'
    script: |
      const fs = require('fs');
      return fs.readFileSync('errors.txt','utf8').toString();
    result-encoding: string

# you can access the output variable in like so
- name: Some action
  uses: whateveryouwant/whatever@4
  if: != 'success'
    something: ${{ steps.error-log.outputs.result }}

# print errors.txt to stdout + fail workflow since build failed
# use `cat` if not using windows
- name: Show build errors
  if: != 'success'
  run: |
    type errors.txt
    exit 1

Note: You can change the output variable name by using core.setOutput as well.

For any lost souls in the future: If you’re setting output in a Docker container (like if your action is a .NET binary), not in the action YML, by just printing ::set-output name=whatever::whatever, all you need to do to fix this is replace any \n you have with %0A

Also for anyone in the future with this issue, I JSON-encoded the content I needed to put into GITHUB_ENV like so:

cat_results=$(cat results/results_blob.txt | python3 -c 'import json; import sys; print(json.dumps(')
echo "RESULTS=${cat_results}" >> $GITHUB_ENV

I kept getting errors with the multiline $GITHUB_ENV. This worked perfectly since I wanted the content JSON-encoded anyway. It was sent over the Github API to create a comment on a PR. You can decode the JSON in another step rather than hoping you caught all url-encoded characters with replace().

I have worked out a generic solution which should allow you do expose any output to a github-script via ::set-output no matter what special characters it contains: