R: Environment Variables

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.
`R_BATCH`:
  Optional – set in a batch session.
`R_COMPLETION`:
  Optional. If set to `FALSE`, comand-line completion is not used. (Not used by Mac OS GUI.)
`R_DEFAULT_PACKAGES`:
  A comma-separated list of packages which are to be loaded in every session. See `options`.
`R_DOC_DIR`:
  The location of the R ‘doc’ directory. Set by R.
`R_DVIPSCMD`:
  The path to `dvips`. Defaults to the value of DVIPS, and if that is unset to a value determined when R was built. Used by `R CMD Rd2dvi`, and at startup to set the default for `options("latexcmd")`, used by `help(offline = TRUE`.
`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`.
`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_LATEXCMD`:
  The path to `latex`. Defaults to the value of LATEX, and if that is unset to a value determined when R was built. Used by `R CMD Rd2dvi`, and at startup to set the default for `options("latexcmd")`, used by `help(offline = TRUE`.
`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_MAKEINDEXCMD`:
  The path to `makeindex`. Defaults at startup to the value of MAKEINDEX, and if that is unset to a value determined when R was built. Used by `R CMD Rd2dvi`.
`R_PAPERSIZE`:
  Optional. Use to set the default for `options("papersize")`, e.g. used by `pdf`, `postscript` and `help(offline = TRUE)`.
`R_PDFLATEXCMD`:
  The path to `pdflatex`. Defaults at startup to the value of `PDFLATEX`, and if that is unset to a value determined when R was built. Used by `R CMD Rd2dvi`.
`R_PDFVIEWER`:
  The path to the default PDF viewer. Used by `R CMD Rd2dvi`.
`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_RD4DVI`:
  Options for `latex` processing of `Rd` files. Used by `R CMD Rd2dvi` and `help(offline = TRUE)`.
`R_RD4PDF`:
  Options for `pdflatex` processing of `Rd` files. Used by `R CMD Rd2dvi`.
`R_SHARE_DIR`:
  The location of the R ‘share’ directory. Set by R.
`R_UNZIPCMD`:
  The path to `unzip`. Sets the default value for `options("unzip")`.
`R_ZIPCMD`:
  The path to `zip`.
`TMPDIR`, `TMP`, `TEMP`:
  Consulted (in that order) when setting the temporary directory. See `tempdir`.
`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.
`PAGER`:
  The path to the default pager.
`R_BROWSER`:
  The path to the default browser. Used to set the default value of `options("browser")`.
`R_PDFVIEWER`:
  The path to the default PDF viewer. Used by `R CMD Rd2dvi`.
`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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