Fix aliases, update readme

cli/execute

@@ -1,3 +1,32 @@
-#!/usr/bin/env bash
+#!/usr/bin/env node
 
-node src $*
+const { execute } = require('../shared/execute');
+const { readFileSync } = require('fs');
+const languages = require('../shared/languages.json');
+
+const [languageName, sourceFile, ...args] = process.argv.slice(2);
+
+(async () => {
+    if (!languageName) {
+        console.error('Provide a language name');
+        return;
+    }
+    
+    if (!sourceFile) {
+        console.error('Provide a source file');
+        return;
+    }
+
+    const source = readFileSync(sourceFile).toString();
+
+    const language = languages.find(language => language.aliases.includes(languageName.toLowerCase()));
+
+    if (!language) {
+        console.error(`${languageName} is not supported by Piston`);
+        return;
+    }
+
+    const { output } = await execute(language, source, args);
+
+    console.log(output);
+})();