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Version: v0.1.0 Latest Latest

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Published: Aug 5, 2019 License: MIT Imports: 11 Imported by: 9



envsubst is a Go package for expanding variables in a string using ${var} syntax. Includes support for bash string replacement functions.


Documentation can be found on GoDoc.

Supported Functions

  • ${var^}
  • ${var^^}
  • ${var,}
  • ${var,,}
  • ${var:position}
  • ${var:position:length}
  • ${var#substring}
  • ${var##substring}
  • ${var%substring}
  • ${var%%substring}
  • ${var/substring/replacement}
  • ${var//substring/replacement}
  • ${var/#substring/replacement}
  • ${var/%substring/replacement}
  • ${#var}
  • ${var=default}
  • ${var:=default}
  • ${var:-default}

Unsupported Functions

  • ${var-default}

  • ${var+default}

  • ${var:?default}

  • ${var:+default}




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func Eval

func Eval(s string, mapping func(string) string) (string, error)

Eval replaces ${var} in the string based on the mapping function.

func EvalEnv

func EvalEnv(s string) (string, error)

EvalEnv replaces ${var} in the string according to the values of the current environment variables. References to undefined variables are replaced by the empty string.

func EvalMap

func EvalMap(s string, values map[string]string) (string, error)

func IsValueNotFoundError

func IsValueNotFoundError(v interface{}) bool


type Template

type Template struct {
	// contains filtered or unexported fields

Template is the representation of a parsed shell format string.

func Parse

func Parse(s string) (t *Template, err error)

Parse creates a new shell format template and parses the template definition from string s.

func ParseFile

func ParseFile(path string) (*Template, error)

ParseFile creates a new shell format template and parses the template definition from the named file.

func (*Template) Execute

func (t *Template) Execute(mapping func(node string, key string, args []string) (string, []string, error)) (str string, err error)

Execute applies a parsed template to the specified data mapping.


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