Sys.setenv {base}R Documentation

Set or Unset Environment Variables

Description

Sys.setenv sets environment variables (for other processes called from within R or future calls to Sys.getenv from this R process).

Sys.unsetenv removes environment variables.

Usage

Sys.setenv(...)

Sys.unsetenv(x)

Arguments

... named arguments with values coercible to a character string.
x a character vector, or an object coercible to character.

Details

The names setenv and putenv come from different Unix traditions: R also has Sys.putenv, but this is now deprecated. The internal code uses setenv if available, otherwise putenv.

Non-standard R names must be quoted in Sys.setenv: see the examples. Most platforms (and POSIX) do not allow names containing "=".

There may be system-specific limits on the maximum length of the values of individual environment variables or of all environment variables. Windows has a limit of 32,767 characters on the environment block, and cmd.exe has a limit of 2047 (Windows 2000) or 8192 characters (XP and later) for each value.

Value

A logical vector, with elements being true if (un)setting the corresponding variable succeeded. (For Sys.unsetenv this includes attempting to remove a non-existent variable.)

Note

Not all systems need support Sys.setenv (although all known current platforms do) nor Sys.unsetenv. Both are provided on Windows (although C-level unsetenv is not available).

See Also

Sys.getenv, Startup for ways to set environment variables for the R session.

setwd for the working directory.

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

Examples

print(Sys.setenv(R_TEST="testit", "A+C"=123))  # `A+C` could also be used
Sys.getenv("R_TEST")
Sys.unsetenv("R_TEST")
Sys.getenv("R_TEST", unset=NA)

[Package base version 2.9.1 Index]