Using ack to effectively search and RStudio project directory

I'm interested in running ack search on a RStudio project directory that mostly contains *.R script files but also some project files and often *.git files. # Directory The project folder structure created from a default Shiny application: $ tree . ├── SomeNosense.Rproj ├── server.R └── ui.R # Search Given this I'm interested in running a simple search for a word ***old*** across the ***.R** files only. *The sample shiny app created as a defult projects has some strings where the word **old** is mentioned*. ack -i -rr 'Old' I'm getting results that do not match what should correspond to ack --help-types, which shows: --[no]rr .R ## Results whereas my results for this command are very messy: .Rproj.user/38B87E11/sdb/s-FEC4716C/28624A5C 7: "folds" : "", .Rproj.user/38B87E11/sdb/s-FEC4716C/8A580C19 3: "contents" : "\n# This is the user-interface definition of a Shiny web application.\n# You can find out more about building applications with Shiny here:\n#\n# http://shiny.rstudio.com\n#\n\nlibrary(shiny)\n\nshinyUI(fluidPage(\n\n # Application title\n titlePanel(\"Old Faithful Geyser Data\"),\n\n # Sidebar with a slider input for number of bins\n sidebarLayout(\n sidebarPanel(\n sliderInput(\"bins\",\n \"Number of bins:\",\n min = 1,\n max = 50,\n value = 30)\n ),\n\n # Show a plot of the generated distribution\n mainPanel(\n plotOutput(\"distPlot\")\n )\n )\n))\n", 7: "folds" : "", ui.R 13: titlePanel("Old Faithful Geyser Data"), # Desired results Desired results can be achieved with grep: me-547/47:SomeNosense$ grep -r -i 'old' ~/Documents/SomeNosense/*.R /Users/me/Documents/SomeNosense/ui.R: titlePanel("Old Faithful Geyser Data"), # Question What is wrong with my [tag:ack] command that I'm not getting the same results? --- The ag also seems to be returning more accurate results: me-552/52:SomeNosense$ ag -rr -i 'old' ui.R 13: titlePanel("Old Faithful Geyser Data"), me-553/53:SomeNosense$ ack -rr -i 'old' .Rproj.user/38B87E11/sdb/per/t/28624A5C 7: "folds" : "", .Rproj.user/38B87E11/sdb/per/t/8A580C19 3: "contents" : "\n# This is the user-interface definition of a Shiny web application.\n# You can find out more about building applications with Shiny here:\n#\n# http://shiny.rstudio.com\n#\n\nlibrary(shiny)\n\nshinyUI(fluidPage(\n\n # Application title\n titlePanel(\"Old Faithful Geyser Data\"),\n\n # Sidebar with a slider input for number of bins\n sidebarLayout(\n sidebarPanel(\n sliderInput(\"bins\",\n \"Number of bins:\",\n min = 1,\n max = 50,\n value = 30)\n ),\n\n # Show a plot of the generated distribution\n mainPanel(\n plotOutput(\"distPlot\")\n )\n )\n))\n", 7: "folds" : "", ui.R 13: titlePanel("Old Faithful Geyser Data"), RStudio: 1.0.143