> For the complete documentation index, see [llms.txt](https://altaisoft.gitbook.io/ysv/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://altaisoft.gitbook.io/ysv/language/constants.md).

# Constants

Fill in constant values

## value

```yaml
version: 1
columns:
  copyright:
    - value: "©2020 Acme Labs, Inc"
```

Fills every cell in the output dataset with a static value hardcoded in the config.

## var

```yaml
version: 1
columns:
  operating_system:
    - var: operating_system
```

To get desired result, run `ysv` like this:

```bash
YSV_VAR_operating_system=VMS cat input.csv | ysv operating_sytems.yaml > output.csv
```

Useful to employ `ysv` in automated environments and scripts.

## line-number

```yaml
version: 1
columns:
  line:
    - line-number
```

Will enumerate dataset lines, starting from 1.