running r scripts or commands with interpretor in unix for unix-layman

Question

I am layman to unix and sofar I using R in windows. For example I type following in my R session (in R gui).

# this is a my funny example script 
X <- 1:         


        

Answer 1

The examples below show two ways to run R code in a shell script. Both examples will also define functions without executing them, if the scripts are loaded to an interactive R session via the source() function.

The first example allows you to give arguments as you would to any other shell script, but will not pass additional R-options to R (because Rscript gives "--args" to R as one of the arguments).

The second example allows you to give additional R-options, but generates (harmless) warning messages unless you give "--args" as one of the script arguments. This version is best avoided unless you have special requirements.

prototype-Rscript.r

#!/usr/bin/env Rscript
# Prototype R script for use at command line in Linux, Mac OS X, UNIX

# References:
#   Manual "A Introduction to R", available via help.start() from the R Console
#   Appendix "B.1 Invoking R from the command line" in "A Inroduction to R",

showArguments <- function(argv)  {
    print(argv)
    0
}

if ( ! interactive() )  {
    # set some error return codes
    SCRIPT_ERROR <- 10                      # see documentation for quit()
    SCRIPT_ARG_ERROR <- SCRIPT_ERROR + 1

    # Define ARGV as script path concatenated to script arguments
    ARGV <- commandArgs(FALSE)          # start with all the arguments given to R
    scriptPath <- sub("^--file=", "", grep("^--file=", ARGV, value=TRUE)) [[1]]
    ARGV <- c(scriptPath, commandArgs(TRUE))

    if (length(ARGV) < 2)   {
        cat(file=stderr(), sep="",
            "Usage: ", ARGV[[1]], " [ options ] item ...\n",
            "       Do something with item\n",
            "       See script for details\n")
        quit(save="no", status=SCRIPT_ARG_ERROR)
    }
    quit(save="no", status=showArguments(ARGV))
}

prototype-shellscript.r

#!/usr/bin/env R --slave --vanilla --quiet -f
# Prototype R script for use at command line in Linux, Mac OS X, UNIX

# References:
#   Manual "A Introduction to R", available via help.start() from the R Console
#   Appendix "B.1 Invoking R from the command line" in "A Inroduction to R",

showArguments <- function(argv)  {
    print(argv)
    0
}

if ( ! interactive() )  {
    # set some error return codes
    SCRIPT_ERROR <- 10                      # see documentation for quit()
    SCRIPT_ARG_ERROR <- SCRIPT_ERROR + 1

    # Define ARGV as the arguments given to this script (after argument “-f”)
    ARGV <- commandArgs(FALSE)          # start with all the arguments given to R
    ARGV <- ARGV[(grep("-f", ARGV) [[1]] + 1):length(ARGV)]
    if ( any(grepl("--args", ARGV) ))   {   # remove arguments intended only for R
        ARGV <- c(ARGV[[1]], commandArgs(TRUE))
    }

    if (length(ARGV) < 2)   {
        cat(file=stderr(), sep="",
            "Usage: ", ARGV[[1]], " [ R_options ] --args [ options ] item ...\n",
            "       Do something with item\n",
            "       See script for details\n")
        quit(save="no", status=SCRIPT_ARG_ERROR)
    }
    quit(save="no", status=showArguments(ARGV))
}