base (version 3.4.1)

Sys.getenv: Get Environment Variables

Description

Sys.getenv obtains the values of the environment variables.

Usage

Sys.getenv(x = NULL, unset = "", names = NA)

Arguments

x

a character vector, or NULL.

unset

a character string.

names

logical: should the result be named? If NA (the default) single-element results are not named whereas multi-element results are.

Value

A vector of the same length as x, with (if names == TRUE) the variable names as its names attribute. Each element holds the value of the environment variable named by the corresponding component of x (or the value of unset if no environment variable with that name was found).

On most platforms Sys.getenv() will return a named vector giving the values of all the environment variables, sorted in the current locale. It may be confused by names containing = which some platforms allow but POSIX does not. (Windows is such a platform: there names including = are truncated just before the first =.)

When x is missing and names is not false, the result is of class "Dlist" in order to get a nice print method.

Details

Both arguments will be coerced to character if necessary.

Setting unset = NA will enable unset variables and those set to the value "" to be distinguished, if the OS does. POSIX requires the OS to distinguish, and all known current R platforms do.

See Also

Sys.setenv, Sys.getlocale for the locale in use, getwd for the working directory.

The help for ‘environment variables’ lists many of the environment variables used by R.

Examples

## whether HOST is set will be shell-dependent e.g. Solaris' csh does not.
Sys.getenv(c("R_HOME", "R_PAPERSIZE", "R_PRINTCMD", "HOST"))

names(s <- Sys.getenv()) # all settings (the values could be very long)
head(s, 12)# using the Dlist print() method

## Language and Locale settings -- but rather use Sys.getlocale()
s[grep("^L(C|ANG)", names(s))]