Details of some of the environment variables which affect an R session.
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.
Some Windows-specific variables are
GSC:Optional: the path to Ghostscript, used if
R_GSCMD is not set.
R_USER:The user's ‘home’ directory. Set by
R. (HOME will be set to the same value if not already set.)
TZDIR:Optional. The top-level directory of the
time-zone database. See Sys.timezone.
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 the macOS 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).
For Rgui it controls the number of lines saved to the
history file: the size of the history used in the session is
controlled by the console customization: see Rconsole.
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_PCRE_JIT_STACK_MAXSIZE:Optional. Consulted when
PCRE's JIT pattern compiler is first used. See grep.
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 time zone. 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.
Sys.getenv and Sys.setenv to read and set
environmental variables in an R session.
gctorture for environment variables controlling garbage
collection.