> ## Documentation Index
> Fetch the complete documentation index at: https://errand.nuvrel.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# regexreplace

> Replace all regex matches in a string.

`regexreplace(str, pattern, replace)` replaces every match of `pattern` in `str` with `replace`. Uses RE2 regular expression syntax.

## Signature

```
regexreplace(str string, pattern string, replace string) string
```

## Example

Sanitize a git branch name for use as a Kubernetes namespace. Namespaces must be lowercase, alphanumeric, and hyphenated with no leading or trailing hyphens:

```hcl theme={null}
variable "branch" {
  description = "Git branch name"
  type        = string
}

computed "namespace" {
  description = "Kubernetes namespace derived from the branch"
  expression  = lower(regexreplace(var.branch, "[^a-z0-9]", "-"))
}

task "deploy-preview" {
  description = "Deploy a preview environment for this branch"
  commands = [
    "kubectl create namespace ${computed.namespace} --dry-run=client -o yaml | kubectl apply -f -",
    "helm upgrade --install preview-${computed.namespace} ./chart --namespace ${computed.namespace}",
  ]
}
```

`feature/My-Branch` becomes `feature-my-branch`.

## Notes

* The pattern must be a valid RE2 expression. RE2 does not support lookahead or backreferences.
* `replace` can include `$1`, `$2`, etc. to reference capture groups.
* For simple string substitution without regular expressions, use [`replace`](/functions/string/replace).