在 R 中抑制 system() 输出

Question

我想将invisible()函数行为应用于我在脚本中得到的输出，如下所示system("cmd.exe", input = command)。然而，即使使用不可见，输出仍然显示在控制台中。有什么办法可以隐藏它吗？

编辑：我正在curl命令中运行来下载网页，输出是预期的curl 输出。

EDIT2：可重现的示例

url <- "www.google.com"
command <- paste0('curl "', 
                  url,
                  '"',
                  ' -H "Pragma: no-cache" -H "Accept-Encoding: gzip, deflate, br" -H "Accept-Language: en-US,en;q=0.9" -H "Upgrade-Insecure-Requests: 1" -H "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36" -H "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8" -H "Cache-Control: no-cache" -H "Cookie: uupid69991=eb4c8ec5-1f94-4cf5-957d-e477a778f79c; uupid99993=eb4c8ec5-1f94-4cf5-957d-e477a778f79c; uupid89991=1; uupid79991=Fee_Based_Role; locale=en; uupid99991=1903 x 1012; IVZSESSIONID=CEHrDvYqpDuQ-zwy8YZpWwm1RWZHY3DGq4V7elBfxcH87XFFo-J_^! -175310928; _ga=GA1.2.1974800928.1524362050; _gid=GA1.2.1544243785.1524362050" -H "Connection: keep-alive" --compressed',
                  ' > google.html')

invisible(system("cmd.exe", input = command))

控制台输出：

Microsoft Windows [Version 10.0.16299.371]
(c) 2017 Microsoft Corporation. All rights reserved.

C:\Users\gonza\OneDrive\Documents\etfcmfa>curl "www.google.com" -H "Pragma: no-cache" -H "Accept-Encoding: gzip, deflate, br" -H "Accept-Language: en-US,en;q=0.9" -H "Upgrade-Insecure-Requests: 1" -H "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36" -H "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8" -H "Cache-Control: no-cache" -H "Cookie: uupid69991=eb4c8ec5-1f94-4cf5-957d-e477a778f79c; uupid99993=eb4c8ec5-1f94-4cf5-957d-e477a778f79c; uupid89991=1; uupid79991=Fee_Based_Role; locale=en; uupid99991=1903 x 1012; IVZSESSIONID=CEHrDvYqpDuQ-zwy8YZpWwm1RWZHY3DGq4V7elBfxcH87XFFo-J_^! -175310928; _ga=GA1.2.1974800928.1524362050; _gid=GA1.2.1544243785.1524362050" -H "Connection: keep-alive" --compressed > google.html
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   231  100   231    0     0    982      0 --:--:-- --:--:-- --:--:--   982

Answer 1

intern=TRUE在您的系统调用中使用。从system帮助页面：

intern  
a logical (not NA) which indicates whether to capture the output of the command as an R character vector.

一旦你这样做了，你可以使用不可见或只是存储结果以防止它们被打印。