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).

DVIPS:

The path to dvips. Used at startup to set the default for options("dvipscmd") which used by the deprecated help(help_type="ps").

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.

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.