我在Linux shell脚本中运行R，我需要代码自行运行。目前我必须在这里运行install.packages（＆＃34; RJDBC＆＃34;）并且它不停地暂停代码以询问CRAN镜像（在我的情况下，我需要它为51）。
换句话说，我运行下面的代码，我需要它来避免问我CRAN镜像是什么，我需要在不停止代码的情况下自动选择它。 （＆gt;之后的所有内容都是我在代码停止之前运行的），其余的都输出。
> #Libraries and Packages--------------
> install.packages("RJDBC") #Selection: 51 (Spain (Madrid))
[1] Installing package into ‘/usr/lib64/R/library’
(as ‘lib’ is unspecified)
--- Please select a CRAN mirror for use in this session ---
Secure CRAN mirrors
1: 0-Cloud [https] 2: Algeria [https]
3: Australia (Canberra) [https] 4: Australia (Melbourne 1) [https]
5: Australia (Melbourne 2) [https] 6: Australia (Perth) [https]
7: Austria [https] 8: Belgium (Ghent) [https]
9: Brazil (PR) [https] 10: Brazil (RJ) [https]
11: Brazil (SP 1) [https] 12: Brazil (SP 2) [https]
13: Bulgaria [https] 14: Chile 1 [https]
15: Chile 2 [https] 16: China (Guangzhou) [https]
17: China (Lanzhou) [https] 18: China (Shanghai 1) [https]
19: China (Shanghai 2) [https] 20: Colombia (Cali) [https]
21: Czech Republic [https] 22: Denmark [https]
23: East Asia [https] 24: Ecuador (Cuenca) [https]
25: Ecuador (Quito) [https] 26: Estonia [https]
27: France (Lyon 1) [https] 28: France (Lyon 2) [https]
29: France (Marseille) [https] 30: France (Montpellier) [https]
31: France (Paris 2) [https] 32: Germany (Erlangen) [https]
33: Germany (Göttingen) [https] 34: Germany (Münster) [https]
35: Greece [https] 36: Iceland [https]
37: India [https] 38: Indonesia (Jakarta) [https]
39: Ireland [https] 40: Italy (Padua) [https]
41: Japan (Tokyo) [https] 42: Japan (Yonezawa) [https]
43: Korea (Seoul 1) [https] 44: Korea (Ulsan) [https]
45: Malaysia [https] 46: Mexico (Mexico City) [https]
47: Norway [https] 48: Philippines [https]
49: Serbia [https] 50: Spain (A Coruña) [https]
51: Spain (Madrid) [https] 52: Sweden [https]
53: Switzerland [https] 54: Turkey (Denizli) [https]
55: Turkey (Mersin) [https] 56: UK (Bristol) [https]
57: UK (Cambridge) [https] 58: UK (London 1) [https]
59: USA (CA 1) [https] 60: USA (IA) [https]
61: USA (KS) [https] 62: USA (MI 1) [https]
63: USA (NY) [https] 64: USA (OR) [https]
65: USA (TN) [https] 66: USA (TX 1) [https]
67: Vietnam [https] 68: (other mirrors)
Selection: