R 闪亮的服务器，无法插入openxlsx绘图

使用runApp（）从控制台运行以下闪亮的应用程序时，它会按预期工作，显示绘图，并提供下载嵌入绘图的excel文件的功能。在闪亮服务器上运行相同的应用程序会产生错误

无法打开文件“Rplots.pdf”

• 闪亮服务器v1.4.2.786
• Node.js v0.10.40
• R版本3.3.1（2016-06-21）-“头发上的虫子”
• Ubuntu 14.04.4 LTS

  library(shiny)
  library(openxlsx)
  library(magrittr)
  
  # Define UI for application that draws a histogram
  ui <- shinyUI(fluidPage(
  
     # Application title
     titlePanel("Old Faithful Geyser Data"),
  
     # Sidebar with a slider input for number of bins 
     sidebarLayout(
        sidebarPanel(
           sliderInput("bins",
                       "Number of bins:",
                       min = 1,
                       max = 50,
                       value = 30),
           downloadButton('specDataDownload',
                          label = "Download",
                          class = NULL)
        ),
  
        # Show a plot of the generated distribution
        mainPanel(
           plotOutput("distPlot")
        )
     )
  ))
  
  # Define server logic required to draw a histogram
  server <- shinyServer(function(input, output) {
  
     output$distPlot <- renderPlot({
        # generate bins based on input$bins from ui.R
        x    <- isolate({faithful[, 2] })
        bins <- seq(min(x), max(x), length.out = input$bins + 1)
  
        # draw the histogram with the specified number of bins
        hist(x, breaks = bins, col = 'darkgray', border = 'white')
  
     })
     output$specDataDownload <- downloadHandler(
         filename = function() {
             paste("ProcessedPlateAssay",
                   gsub("-|[[:space:]]|:",
                        "",
                        Sys.time()),
                   ".xlsx",
                   sep = "_")
         },
         content = function(con) {
             x    <- isolate({faithful[, 2] })
             bins <- seq(min(x), max(x), length.out = input$bins + 1)
             output <- createWorkbook()
             addWorksheet(
                 output,
                 "One")
             hist(
                 x,
                 breaks = bins,
                 col = 'darkgray',
                 border = 'white')
             insertPlot(
                 output,
                 sheet = 1,
                 startRow = (1),
                 startCol = 5,
                 width = 6.5,
                 height = 3,
                 fileType = "png",
                 units = "in",
                 dpi = 600)
  
         saveWorkbook(
             wb = output,
             file = con
         )
         })
  })
  
  # Run the application 
  shinyApp(ui = ui, server = server)
  

  库（闪亮）
  库（openxlsx）
  图书馆（magrittr）
  #为绘制直方图的应用程序定义UI
  ui我想提供一个简单的例子，因为我一直在努力解决
  openxlsx
  的
  insertPlot
  函数在闪亮服务器中不工作的问题，可能是由于
  tempfile
  或
  dev.copy
  的权限问题。对我来说最有效的方法是使用
  ggsave
  ，因为它可以非常灵活地处理分辨率，并且还有一个缩放参数，可以调整图像元素的大小，使其更适合演示。我还包括了使用
  png
  函数的第二种方法
  
  下面是一个可复制的示例，部分来自于中@sebkopf的答案
  
  库（闪亮）
  库（openxlsx）
  图书馆（GG2）
  ui遇到了同样的问题。我们是这样解决的：（1）使用jpeg打开（临时）绘图；（2） 执行plot命令，（3）关闭jpeg，使用insertImage。嗨，我最终也解决了这个问题，但根本问题是我服务器上的闪亮用户没有对文件夹的写入权限（它被创建为git存储库并推送到服务器）。请记住检查Shinny是否是您试图写入的目录的所有者：通过
  sudo chown shinny:shinny/var/shinny server/www/shinny_test/work
  library(shiny)
  library(openxlsx)
  library(ggplot2)
  
  ui <- fluidPage(
    downloadLink("downloadExcel", "Excel Graph Download")
  )
  
  server <- function(input, output) {
  
    p1 <- qplot(mpg, data=mtcars, geom="density", fill=as.factor(gear), 
  alpha=I(.5), main="Distribution of Gas Mileage")
    p2 <- qplot(age, circumference, data = Orange, geom = c("point", "line"), 
  colour = Tree)
  
    output$downloadExcel <- downloadHandler(
      filename = "savePlot.xlsx",
      content = function(file){
        wb <- createWorkbook()
  
        addWorksheet(wb, "ggsave", gridLines = F)
        addWorksheet(wb, "png", gridLines = F)
  
        # Method 1: using ggsave
  
        ggsave("p1.png", plot = p1, scale = .6) # Scale parameter resizes the object making text more legible
        ggsave("p2.png", plot = p2, scale = .6)
  
        insertImage(wb, "ggsave", "p1.png", width = 5, height = 3.5)
        insertImage(wb, "ggsave", "p22.png", startCol = "J", width = 16, height = 10, units = "cm")
  
        # Method 2: using png function
  
        png("p11.png")
        print(p1)
        dev.off()
  
        insertImage(wb, "png", "p11.png", width = 5, height = 3.5)
  
        png("p22.png")
        print(p2)
        dev.off()
  
        insertImage(wb, "png", "p22.png", startCol = "J", width = 16, height = 10, units = "cm")
  
        saveWorkbook(wb, file, overwrite = T)
  
        unlink(c("p1", "p2", "p11", "p22")) # To remove the images from the server
      }
    )
  }
  
  shinyApp(ui, server)