| % File src/library/base/man/Sys.getenv.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2014 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{Sys.getenv} |
| \title{Get Environment Variables} |
| \usage{ |
| Sys.getenv(x = NULL, unset = "", names = NA) |
| } |
| \alias{Sys.getenv} |
| \arguments{ |
| \item{x}{a character vector, or \code{NULL}.} |
| \item{unset}{a character string.} |
| \item{names}{logical: should the result be named? If \code{NA} (the |
| default) single-element results are not named whereas multi-element |
| results are.} |
| } |
| \description{ |
| \code{Sys.getenv} obtains the values of the environment variables. |
| } |
| \details{ |
| Both arguments will be coerced to character if necessary. |
| |
| Setting \code{unset = NA} will enable unset variables and those set to |
| the value \code{""} to be distinguished, \emph{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 \code{x}, with (if \code{names == |
| TRUE}) the variable names as its \code{names} attribute. Each element |
| holds the value of the environment variable named by the corresponding |
| component of \code{x} (or the value of \code{unset} if no environment |
| variable with that name was found). |
| |
| On most platforms \code{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 \code{=} which |
| some platforms allow but POSIX does not. (Windows is such a platform: |
| there names including \code{=} are truncated just before the first |
| \code{=}.) |
| |
| When \code{x} is missing and \code{names} is not false, the result is |
| of class \code{"Dlist"} in order to get a nice |
| \code{\link{print}} method. |
| } |
| \seealso{ |
| \code{\link{Sys.setenv}}, |
| \code{\link{Sys.getlocale}} for the locale in use, |
| \code{\link{getwd}} for the working directory. |
| |
| The help for \sQuote{\link{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")) |
| |
| s <- Sys.getenv() |
| \donttest{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))] |
| } |
| \keyword{environment} |
| \keyword{utilities} |