Sys.getenv               package:base               R Documentation

Get Environment Variables

Description:

     'Sys.getenv' obtains the values of the environment variables.

Usage:

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

Arguments:

       x: a character vector, or 'NULL'.

   unset: a character string.

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_.

Value:

     A vector of the same length as 'x', with 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, collated in the
     current locale.  (It may be confused by names containing '"="'
     which some platforms allow but POSIX does not.)

See Also:

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

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)

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

