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
.
R_SUPPORT_OLD_TARS
logical. Sets the default for the
support_old_tars
argument of untar
. Should
be set to TRUE
if an old system tar
command is
used which does not support either xz
compression or
automagically detecting compression type.
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.