Set or Unset Environment Variables (original) (raw)
| Sys.setenv {base} | R Documentation |
|---|
Description
Sys.setenv sets environment variables (for other processes called from within R or future calls to [Sys.getenv](../../base/help/Sys.getenv.html) 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 names+values of all environment variables.
Recent versions of Windows have a maximum length of 32,767 characters for a environment variable; however cmd.exe has a limit of 8192 characters for a command line, hence set can only set 8188.
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
On Unix-alikes, if Sys.unsetenv is not supported, it will at least try to set the value of the environment variable to "", with a warning.
See Also
[Sys.getenv](../../base/help/Sys.getenv.html), Startup for ways to set environment variables for the R session.
[setwd](../../base/help/setwd.html) for the working directory.
[Sys.setlocale](../../base/help/Sys.setlocale.html) to set (and get) language locale variables, and notably [Sys.setLanguage](../../base/help/Sys.setLanguage.html) to set the LANGUAGEenvironment variable which is used for [conditionMessage](../../base/help/conditionMessage.html)translations.
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") # on Unix-alike may warn and not succeed
Sys.getenv("R_TEST", unset = NA)
[Package _base_ version 4.6.0 Index]