R: Set or Unset Environment Variables

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

Non-standard R names must be quoted in `Sys.setenv`: see the examples. Most platforms (and POSIX) do not allow names containing `"="`. Windows does, but the facilities provided by R may not handle these correctly so they should be avoided. Most platforms allow setting an environment variable to `""`, but Windows does not, and there `Sys.setenv(FOO = "")` unsets FOO.

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.)

### 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)

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