https://github.com/kseo/envsubst

Docker style environment variables substitution for Dart
https://github.com/kseo/envsubst

Last synced: 26 days ago
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Docker style environment variables substitution for Dart

• Host: GitHub
• URL: https://github.com/kseo/envsubst
• Owner: kseo
• License: bsd-3-clause
• Created: 2016-09-30T05:47:45.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2016-11-05T15:48:45.000Z (about 8 years ago)
• Last Synced: 2023-08-20T21:53:13.454Z (about 1 year ago)
• Language: Dart
• Homepage: https://pub.dartlang.org/packages/envsubst
• Size: 12.7 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# envsubst

[![Build Status](https://travis-ci.org/kseo/envsubst.svg?branch=master)](https://travis-ci.org/kseo/envsubst)

Docker style environment variables substitution for Dart.

Environment variables are notated either with $variable_name or

${variable_name}. They are treated equivalently and the brace syntax is

typically used to address issues with variable names with no whitespace,

like ${foo}_bar.

The ${variable_name} syntax also supports a few of the standard bash

modifiers as specified below:

* ${variable:-word} indicates that if variable is set then the result will

  be that value. If variable is not set then word will be the result.

* ${variable:+word} indicates that if variable is set then word will be the

  result, otherwise the result is the empty string.

In all cases, word can be any string, including additional environment

variables.

Escaping is possible by adding a \ before the variable: \$foo or \${foo},

for example, will translate to $foo and ${foo} literals respectively.

# Examples

## Using `envsubst` programatically

```dart

import 'package:envsubst/envsubst.dart';

main() {

  String input = r'Hello $HOME';

  String output = envSubst(input);

  print(output); // print 'Hello /Users/kseo'

}

```

## Using via cli

```

$ envsubst.dart < input.txt > output.txt

$ echo 'welcome $HOME' | envsubst

```

# Other Projects

If you are a Go programmer, see [a8m/envsubst][a8m/envsubst].

[a8m/envsubst]: https://github.com/a8m/envsubst