logs: use child_process.spawn directly for sudo

shell.sudo will move to a promise based API shortly

src/logs.js

@@ -1,9 +1,9 @@
 'use strict';
 
 const assert = require('assert'),
+    child_process = require('child_process'),
+    debug = require('debug')('box:logs'),
     path = require('path'),
-    shell = require('./shell.js')('logs'),
-    spawn = require('child_process').spawn,
     stream = require('stream'),
     { StringDecoder } = require('string_decoder'),
     TransformStream = stream.Transform;
@@ -64,14 +64,20 @@ function tail(filePaths, options) {
     assert.strictEqual(typeof options, 'object');
 
     const lines = options.lines === -1 ? '+1' : options.lines;
-    const args = options.sudo ? [ LOGTAIL_CMD ] : [];
+    const args = [ `--lines=${lines}` ];
-    args.push(`--lines=${lines}`);
     if (options.follow) args.push('--follow');
 
     if (options.sudo) {
-        return shell.sudo(args.concat(filePaths), { quiet: true }, () => {});
+        const cp = child_process.spawn('/usr/bin/sudo', [ '-S', LOGTAIL_CMD, ...args, ...filePaths ]);
+        cp.terminate = () => { // see note in shell.js
+            child_process.spawn('kill', ['-SIGKILL', -cp.pid], { detached: true }, (error) => {
+                if (error) debug(`tail could not terminate`, error);
+            });
+        };
+        cp.stdin.end();
+        return cp;
     } else {
-        const cp = spawn('/usr/bin/tail', args.concat(filePaths));
+        const cp = child_process.spawn('/usr/bin/tail', args.concat(filePaths));
         cp.terminate = () => cp.kill('SIGKILL');
         return cp;
     }