Implements #364

README.md

@@ -134,7 +134,7 @@ emitter.clone('path/to/dest').then(() => {
 
 ## Actions
 
-You can manipulate repositories after they have been cloned with _actions_, specified in a `degit.json` file that lives at the top level of the working directory. Currently, there are two actions — `clone` and `remove`. Additional actions may be added in future.
+You can manipulate repositories after they have been cloned with _actions_, specified in a `degit.json` file that lives at the top level of the working directory. Currently, there are three actions — `clone`, `remove`, and `search_replace`. Additional actions may be added in future.
 
 ### clone
 
@@ -164,6 +164,26 @@ This will clone `user/another-repo`, preserving the contents of the existing wor
 
 Remove a file at the specified path.
 
+### search_replace
+
+```json
+// degit.json
+[
+	{
+		"action": "search_replace",
+		"files": [
+			"one.txt",
+			"two.json",
+			"three.mjs"
+		],
+		"pattern": "\\{\\{name\\}\\}",
+		"replacement": "PROJECT_NAME"
+	}
+]
+```
+
+This will perform a search-and-replace in the given plaintext files. For example, this can be used to populate a project with an initial name, or various "author" references with email addresses, etc. The replacement regular expression is defined by the `pattern` field; matches in those files will be replaced by the value of the environmental variable identified by the `replacement` value in the user runtime. For example, the configuration listed above will replace all occurances of `{{name}}` in the given files with the value of the environmental variable `$PROJECT_NAME`.
+
 ## See also
 
 - [zel](https://github.com/vutran/zel) by [Vu Tran](https://twitter.com/tranvu)

src/index.js

@@ -1,3 +1,4 @@
+import process from 'process';
 import fs from 'fs';
 import path from 'path';
 import tar from 'tar';
@@ -70,7 +71,8 @@ class Degit extends EventEmitter {
 					process.exit(1);
 				});
 			},
-			remove: this.remove.bind(this)
+			remove: this.remove.bind(this),
+			search_replace: this.search_replace.bind(this)
 		};
 	}
 
@@ -158,6 +160,17 @@ class Degit extends EventEmitter {
 		}
 	}
 
+	search_replace(dir, dest, action) {
+		const re = new RegExp(action.pattern, 'g');
+		const value = process.env[action.replacement];
+		action.files.forEach(file => {
+			const file_path = `${dest}${path.sep}${file}`;
+			let contents = fs.readFileSync(file_path, "utf8");
+			contents = contents.replace(re, value);
+			fs.writeFileSync(file_path, contents);
+		});
+	}
+
 	_checkDirIsEmpty(dir) {
 		try {
 			const files = fs.readdirSync(dir);