commandArgs

From R.utils v1.9.6 by Henrik Bengtsson

Extract Command Line Arguments

Provides access to a copy of the command line arguments supplied when this Rsession was invoked. This function is backward compatible with commandArgs() of the base package, but adds more features.

Keywords: programming

Usage

commandArgs(asValues=FALSE, excludeReserved=FALSE, excludeEnvVars=FALSE, os=NULL, ...)

Arguments

asValues: If TRUE, a named list is returned, where command line arguments of type --foo will be returned as
excludeReserved: If TRUE, arguments reserved by Rare excluded, otherwise not. Which the reserved arguments are depends on operating system. For details, see Appendix B on "Invoking R" in An Intro
excludeEnvVars: If TRUE, arguments that assigns environment variable are excluded, otherwise not. As described in R --help, these are arguments of format =.
os: A vector of character strings specifying which set of reserved arguments to be used. Possible values are "unix", "mac
...: Passed to commandArgs() of the base package.

Details

This function should be fully backward compatible with the same function in the base package.

Value

If asValue is FALSE, a character vector is returned, which contains the name of the executable and the non-parsed user-supplied arguments. If asValue is TRUE, a named list containing is returned, which contains the the executable and the parsed user-supplied arguments. The first element is the name of the executable by which Rwas invoked. As far as I am aware, the exact form of this element is platform dependent. It may be the fully qualified name, or simply the last component (or basename) of the application. The attribute isReserved is a logical vector specifying if the corresponding command line argument is a reserved Rargument or not.

Examples

######################################################################
# Non-parsed command-line arguments
######################################################################
# Display how this instance of R was invoked.
cmd <- paste(commandArgs(), collapse="")
cat("How R was invoked:
");
cat(cmd, "")

# Get all arguments
args <- commandArgs()
print(args)

# Get only "private" arguments and not the name of the R executable.
args <- commandArgs(excludeReserved=TRUE)[-1]
print(args)

# Assert backward compatibility
args0 <- base::commandArgs()
args <- commandArgs()
stopifnot(all.equal(args, args0, check.attributes=FALSE))


######################################################################
# Parsed command-line arguments
######################################################################
# Get all arguments as a named list, e.g. if R is started as:
#
#   R DATAPATH=../data --args --root="do da" --foo bar --details --a=2
#
# then 'args' below will equal
#
#   list(R=NA, DATAPATH="../data" args=TRUE, root="do da",
#        foo="bar", details=TRUE, a="2")
args <- commandArgs(asValue=TRUE)
str(args)

# Turn arguments into R variables
args <- commandArgs(asValue=TRUE, excludeReserved=TRUE)[-1]
keys <- attachLocally(args)
cat("Command-line arguments attached to global environment:
");
print(keys);
str(mget(keys, envir=globalenv()))

Documentation reproduced from package R.utils, version 1.9.6, License: LGPL (>= 2.1)

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