---
title: Migrating to v8
description: Changes to exec scripts and build numbers when moving from Melos 7 to Melos 8.
---
> ## Documentation Index
> Fetch the complete documentation index at: https://melos.invertase.dev/llms.txt
> Use this file to discover all available pages before exploring further.

## Configure `exec` scripts

How you configure an `exec` script with options has changed. Previously, the
command was specified in `run` and the `melos exec` options in `exec`:

```yaml
# Before (no longer supported)

melos:
  scripts:
    test:
      run: dart test --concurrency=1
      exec:
        concurrency: 1
```

`run` and `exec` are mutually exclusive: a script either runs once in the
workspace root with `run`, or across multiple packages with `exec`. When you
need to pass options to `exec`, move the command into `exec` under the
`command` key:

```yaml
# After

melos:
  scripts:
    test:
      exec:
        command: dart test --concurrency=1
        concurrency: 1
```

The shorthand form, where `exec` is a string containing the command, is
unchanged:

```yaml
melos:
  scripts:
    hello:
      exec: echo 'Hello $(dirname $PWD)'
```

Melos fails with a descriptive error, including the converted configuration,
if it encounters the old format.

## Build numbers when versioning

`melos version` retains and increments an integer build number on every
version bump, so `3.0.0+11` becomes `4.0.0+12` instead of `4.0.0`.

A patch release below `1.0.0` bumps the patch component instead of adding a
build number, so `0.1.0` becomes `0.1.1` instead of `0.1.0+1`. For more
information, see [Build numbers](/guides/automated-releases#build-numbers).