R: Get Environment Variables (original) (raw)
| Sys.getenv {base} | R Documentation |
|---|
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. |
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.
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](../../base/help/print.html) method.
See Also
[Sys.setenv](../../base/help/Sys.setenv.html),[Sys.getlocale](../../base/help/Sys.getlocale.html) for the locale in use,[getwd](../../base/help/getwd.html) 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 did not.
Sys.getenv(c("R_HOME", "R_PAPERSIZE", "R_PRINTCMD", "HOST"))
s <- Sys.getenv() # *all* environment variables
op <- options(width=111) # (nice printing)
names(s) # 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))]
## typically R-related:
s[grep("^_?R_", names(s))]
options(op)# reset
[Package _base_ version 4.6.0 Index]