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rbashdockerrscript

Multi-Line Rscript in Dockerfile

I am trying to build a docker image with R, and I'd like to be able to break out my package install steps in a clean, easy to read, manner across multiple lines, but bash does not seem to like the approach due to not knowing where the ending ) is.

Is there a way to make this long line of code split across multiple lines?

Rscript -e 'devtools::install_cran(c("tidytext","janitor","corrr","officer","devtools","pacman"))'

To maybe, something like this:

Rscript -e 'devtools::install_cran(c("tidytext","janitor",
                              "corrr","officer","devtools","pacman"))'

Is this possible to do with Rscript? I have tried using a \ at the end of each line, and it still does not work.

I understand install2.r can list out the packages line by line, but I would like to have a vector of packages to pass to devtools::install_cran if possible. I have seen others simply refer to their R script by simply calling it via Rscript, but I would like to see all my installation steps inside my Dockerfile, and not copy and run an external R script in my container. Thanks for your help.

Rscript test.R
Solution

  • BASH will interpret a newline as the end of the command.

    In BASH (which I'm assuming you're using), a backslash followed by a newline is interpreted as a continuation of the line. Except when it is inside single quotes!

    So...

    Rscript -e 'devtools::install_cran(c("tidytext","janitor",
                          "corrr","officer","devtools","pacman"))'

    will be interpreted as two commands...

    Rscript -e 'devtools::install_cran(c("tidytext","janitor",

    and

    "corrr","officer","devtools","pacman"))'

    Neither of which are well formed.

    Additionally, single quoted strings in BASH will not handle escapes. They simply assume your text is literal. So you cannot continue a line within single quoted strings in BASH.

    The bottom line is that if you want continuation within a quoted string in BASH, you must use double quoted strings. Your options are as follows:

    Rscript -e "devtools::install_cran(c('tidytext','janitor', \  
                'corrr','officer','devtools','pacman'))"

    using double quotes in BASH and single quotes in R or...

    Rscript -e "devtools::install_cran(c(\"tidytext\",\"janitor\", \    
                \"corrr\",\"officer\",\"devtools\",\"pacman\"))"

    using double quotes in both.