Sys.setenv
Set or Unset Environment Variables
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.
- Keywords
- utilities, environment
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.)
Note
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, 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
library(base)
# NOT RUN {
print(Sys.setenv(R_TEST = "testit", "A+C" = 123)) # `A+C` could also be used
Sys.getenv("R_TEST")
Sys.unsetenv("R_TEST")
Sys.unsetenv("R_TEST") # may warn and not succeed
Sys.getenv("R_TEST", unset = NA)
# }