EnvVar {base} | R Documentation

## Environment Variables

### Description

Details of some of the environment variables which affect an R session.

### Details

It is impossible to list all the environment variables which can affect an R session: some affect the OS system functions which R uses, and others will affect add-on packages. But here are notes on some of the more important ones. Those that set the defaults for options are consulted only at startup (as are some of the others).

HOME:

  The user's ‘home’ directory.

LANGUAGE:

  Optional. The language(s) to be used for message translations. This is consulted when needed.

LC_ALL:

  (etc) Optional. Use to set various aspects of the locale – see `Sys.getlocale`. Consulted at startup.

MAKEINDEX:

  The path to `makeindex`. If unset to a value determined when R was built. Used by the emulation mode of `texi2dvi` and `texi2pdf`.

R_BATCH:

  Optional – set in a batch session, that is one started by `R CMD BATCH`. Most often set to `""`, so test by something like `!is.na(Sys.getenv("R_BATCH", NA))`.

R_BROWSER:

  The path to the default browser. Used to set the default value of `options("browser")`.

R_COMPLETION:

  Optional. If set to `FALSE`, command-line completion is not used. (Not used by Mac OS GUI.)

R_DEFAULT_PACKAGES:

  A comma-separated list of packages which are to be attached in every session. See `options`.

R_DOC_DIR:

  The location of the R ‘doc’ directory. Set by R.

R_ENVIRON:

  Optional. The path to the site environment file: see Startup. Consulted at startup.

R_GSCMD:

  Optional. The path to Ghostscript, used by `dev2bitmap`, `bitmap` and `embedFonts`. Consulted when those functions are invoked. Since it will be treated as if passed to `system`, spaces and shell metacharacters should be escaped.

R_HISTFILE:

  Optional. The path of the history file: see Startup. Consulted at startup and when the history is saved.

R_HISTSIZE:

  Optional. The maximum size of the history file, in lines. Exactly how this is used depends on the interface. For the `readline` command-line interface it takes effect when the history is saved (by `savehistory` or at the end of a session).

R_HOME:

  The top-level directory of the R installation: see `R.home`. Set by R.

R_INCLUDE_DIR:

  The location of the R ‘include’ directory. Set by R.

R_LIBS:

  Optional. Used for initial setting of `.libPaths`.

R_LIBS_SITE:

  Optional. Used for initial setting of `.libPaths`.

R_LIBS_USER:

  Optional. Used for initial setting of `.libPaths`.

R_PAPERSIZE:

  Optional. Used to set the default for `options("papersize")`, e.g. used by `pdf` and `postscript`.

R_PDFVIEWER:

  The path to the default PDF viewer. Used by `R CMD Rd2pdf`.

R_PLATFORM:

  The platform – a string of the form `cpu-vendor-os`, see `R.Version`.

R_PROFILE:

  Optional. The path to the site profile file: see Startup. Consulted at startup.

R_RD4PDF:

  Options for `pdflatex` processing of `Rd` files. Used by `R CMD Rd2pdf`.

R_SHARE_DIR:

  The location of the R ‘share’ directory. Set by R.

R_TEXI2DVICMD:

  The path to `texi2dvi`. Defaults to the value of TEXI2DVI, and if that is unset to a value determined when R was built. Consulted at startup to set the default for `options("texi2dvi")`, used by `texi2dvi` and `texi2pdf` in package tools.

R_UNZIPCMD:

  The path to `unzip`. Sets the initial value for `options("unzip")` on a Unix-alike when namespace utils is loaded.

R_ZIPCMD:

  The path to `zip`. Used by `zip` and by `R CMD INSTALL --build` on Windows.

TMPDIR, TMP, TEMP:

  Consulted (in that order) when setting the temporary directory for the session: see `tempdir`. TMPDIR is also used by some of the utilities see the help for `build`.

TZ:

  Optional. The current timezone. See `Sys.timezone` for the system-specific formats. Consulted as needed.

no_proxy, http_proxy, ftp_proxy:

  (and more). Optional. Settings for `download.file`: see its help for further details.

### Unix-specific

Some variables set on Unix-alikes, and not (in general) on Windows.

DISPLAY:

  Optional: used by `X11`, Tk (in package tcltk), the data editor and various packages.

EDITOR:

  The path to the default editor: sets the default for `options("editor")` when namespace utils is loaded.

PAGER:

  The path to the pager with the default setting of `options("pager")`. The default value is chosen at configuration, usually as the path to `less`.

R_PRINTCMD:

  Sets the default for `options("printcmd")`, which sets the default print command to be used by `postscript`.

### See Also

`Sys.getenv` and `Sys.setenv` to read and set environmental variables in an R session.

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