# print

The `print` function writes its arguments as one line to the script's standard output. Use it for the data a
script produces. Standard output is also the step value when the script does not assign
[`output`](/functions/automation/output).

## Usage

```python
print(*args, sep = " ")
```

## Arguments

- **`*args`**

  (Optional) Any number of values. Strings are written as they are. Other values are written in their
  display form, such as `True`, `None`, `[1, "x"]`, or `{"k": "v"}`.
- **`sep`**
  (Optional) Keyword-only. The text placed between values. Defaults to a single space.

## Returns

The return value is `None`.

## Behavior

- Each call writes one line, ending with a newline. A call with no arguments writes an empty line.
- The line goes to the script's stdout channel, subject to the step's output settings and secret masking. For a
  standalone script, that is the program's standard output.
- When a step does not assign [`output`](/functions/automation/output), everything the script printed becomes the
  step value, including the trailing newline.
- Inside [`steps.parallel`](/functions/automation/steps.parallel) tasks, each line is written whole and prefixed with
  the task name, such as `[dev] `. Lines from different tasks can arrive in any order but never interleave within a
  line. A group with a single task writes without a prefix.

Status messages for people belong on stderr: use [`ui.info`](/functions/automation/ui.info),
[`ui.success`](/functions/automation/ui.success), and [`ui.warning`](/functions/automation/ui.warning). Diagnostics
for troubleshooting belong in the log: use [`log.info`](/functions/automation/log.info) and its siblings.

| Function | Channel | Becomes the step value |
| --- | --- | --- |
| `print` | stdout | Yes, when `output` is unset |
| `ui.info`, `ui.success`, `ui.warning` | stderr | No |
| `log.trace` through `log.error` | The Atmos log, at the configured level | No |

## Examples

### Print several values

```python
print("a", 1, True, None, [1, "x"], {"k": "v"})
print("a", "b", "c", sep = ", ")
print("no separator", sep = "")
print()
```

```text
a 1 True None [1, "x"] {"k": "v"}
a, b, c
no separator

```

### Use printed text as the step value

```yaml
steps:
  - name: calc
    type: script
    interpreter: starlark
    script: |
      print("only stdout")
  - name: show
    type: shell
    command: echo 'value={{ .steps.calc.value }}'
```

```text
only stdout
value=only stdout
```

### Print from parallel tasks

```python
def one(n):
    print("task", n)

steps.parallel(tasks = [steps.task(str(n), one, args = [n]) for n in [1, 2]])
```

```text
[1] task 1
[2] task 2
```

The two lines can appear in either order.

## Related

- [`output`](/functions/automation/output) sets the step value explicitly.
- [`ui.info`](/functions/automation/ui.info) and [`log.info`](/functions/automation/log.info) write to other channels.
- [Atmos Automation Language](/automation/language) and the [script step](/steps/type/script#step-output)