GitHub Actions multiline run script fails (YAML block scalar)
Multiline run commands use a YAML block scalar (| keeps newlines, > folds them). Choosing > or mis-indenting lines folds or strips your script so the shell sees a different command than intended.
What this error means
A multiline run command behaves as one folded line, loses newlines, or fails with a shell syntax error after the YAML block scalar mangled it.
# Using '>' folds newlines into spaces, breaking the script:
run: >
echo one
echo two # becomes: echo one echo twoDiagnose it: print the context before you change anything
Most workflow-expression bugs are not syntax errors, they are an expression reading something that is empty. GitHub resolves a missing property to an empty string instead of failing the run, so a wrong reference looks like a logic bug rather than a mistake. Dump the contexts first and you will usually see the answer immediately.
- name: Dump contexts
run: |
echo '--- github ---' ; echo '${{ toJSON(github) }}'
echo '--- needs ---' ; echo '${{ toJSON(needs) }}'
echo '--- steps ---' ; echo '${{ toJSON(steps) }}'
echo '--- matrix ---' ; echo '${{ toJSON(matrix) }}'
echo '--- inputs ---' ; echo '${{ toJSON(inputs) }}'Check the context is allowed where you used it
Contexts are not available everywhere. The same expression can be valid in a step if and invalid in a job if, which is why an expression that works in one workflow fails when moved.
| Where you wrote it | Contexts available there |
|---|---|
run-name | github, inputs, vars |
concurrency | github, inputs, vars |
Top-level env | github, secrets, inputs, vars |
jobs.<id>.if | github, needs, vars, inputs |
jobs.<id>.steps.if | github, needs, strategy, matrix, job, runner, env, vars, steps, inputs |
jobs.<id>.outputs | Full access, including secrets |
Reusable workflow outputs | github, jobs, vars, inputs |
Common causes
Folded scalar (>) used for a script
> joins lines with spaces, collapsing separate commands into one.
Inconsistent indentation in the block
Mismatched indentation truncates or reshapes the script body.
How to fix it
Use the literal block scalar
- Use | (literal) to preserve newlines for multiline scripts.
- Indent every line of the block consistently under run.
- Reserve > for prose-like folding, not shell commands.
- run: |
echo one
echo two
./build.shCatch it before it reaches CI
Every failure in this cluster is statically detectable. actionlint parses workflow expressions, checks context availability against the same rules above, and validates needs references, so these bugs never need to cost you a run.
# one-off
docker run --rm -v "$(pwd):/repo" --workdir /repo rhysd/actionlint:latest -color
# as a job, before anything expensive runs
- uses: actions/checkout@v4
- run: |
bash <(curl -s https://raw.githubusercontent.com/rhysd/actionlint/main/scripts/download-actionlint.bash)
./actionlint -colorHow to prevent it
- Default to | for multiline run blocks.
- Lint workflows so folded-scalar mistakes are caught.