Improve exec system

src/class/Util.ts

@@ -1,6 +1,5 @@
 /* eslint-disable no-param-reassign */
-import { promisify } from 'util';
-import childProcess from 'child_process';
+import { exec, ExecOptions } from 'child_process';
 import nodemailer from 'nodemailer';
 import { Message, PrivateChannel, GroupChannel, Member, User } from 'eris';
 import uuid from 'uuid/v4';
@@ -31,16 +30,27 @@ export default class Util {
    * @param command The command to execute
    * @param options childProcess.ExecOptions
    */
-  public async exec(command: string, options: childProcess.ExecOptions = {}): Promise<string> {
-    const ex = promisify(childProcess.exec);
-    let result: string;
-    try {
-      const res = await ex(command, options);
-      result = `${res.stdout}${res.stderr}`;
-    } catch (err) {
-      return Promise.reject(new Error(`Command failed: ${err.cmd}\n${err.stderr}${err.stdout}`));
-    }
-    return result;
+  public async exec(command: string, options: ExecOptions = {}): Promise<string> {
+    return new Promise((res, rej) => {
+      let error = false;
+      let output = '';
+      const writeFunction = (data: string|Buffer|Error) => {
+        if (data instanceof Error) error = true;
+        output += `${data}`;
+      };
+      const cmd = exec(command, options);
+      cmd.stdout.on('data', writeFunction);
+      cmd.stderr.on('data', writeFunction);
+      cmd.on('error', writeFunction);
+      cmd.once('close', (code, signal) => {
+        output += `Command exited with code ${code}${signal ? `/${signal}` : ''}`;
+        cmd.stdout.removeListener('data', writeFunction);
+        cmd.stderr.removeListener('data', writeFunction);
+        cmd.removeListener('error', writeFunction);
+        if (error) rej(output);
+        res(output);
+      });
+    });
   }
 
   /**