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<table width="100%" summary="page for Startup {base}"><tr><td>Startup {base}</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Initialization at Start of an R Session</h2>

<h3>Description</h3>

In R, the startup mechanism is as follows.

Unless --no-environ was given on the command line, R
searches for site and user files to process for setting environment
variables. The name of the site file is the one pointed to by the
environment variable R_ENVIRON; if this is unset,
&lsquo;<var><a href="Rhome.html">R_HOME</a></var>/etc/Renviron.site&rsquo; is used (if it exists,
which it does not in a &lsquo;factory-fresh&rsquo; installation). The name
of the user file can be specified by the R_ENVIRON_USER
environment variable; if this is unset, the files searched for are
&lsquo;.Renviron&rsquo; in the current or in the user's home directory (in
that order). See &lsquo;Details&rsquo; for how the files are read.

Then R searches for the site-wide startup profile file of R code
unless the command line option --no-site-file was given. The
path of this file is taken from the value of the R_PROFILE
environment variable (after <a href="path.expand.html">tilde expansion</a>). If this variable
is unset, the default is &lsquo;<var><a href="Rhome.html">R_HOME</a></var>/etc/Rprofile.site&rsquo;,
which is used if it exists
(which it does not in a &lsquo;factory-fresh&rsquo; installation).
This code is sourced into the base package. Users need to be
careful not to unintentionally overwrite objects in base, and it
is normally advisable to use <code><a href="eval.html">local</a></code> if code needs to be
executed: see the examples.

Then, unless --no-init-file was given, R searches for a user
profile, a file of R code. The path of this file can be specified by
the R_PROFILE_USER environment variable (and
<a href="path.expand.html">tilde expansion</a> will be performed). If this is unset, a file
called &lsquo;.Rprofile&rsquo; is searched for in the current directory or in
the user's home directory (in that order). The user profile file is
sourced into the workspace.

Note that when the site and user profile files are sourced only the
base package is loaded, so objects in other packages need to be
referred to by e.g. <code>utils::dump.frames</code> or after explicitly
loading the package concerned.

R then loads a saved image of the user workspace from &lsquo;.RData&rsquo;
in the current directory if there is one (unless
--no-restore-data or --no-restore was specified on
the command line).

Next, if a function <code>.First</code> is found on the search path,
it is executed as <code>.First()</code>. Finally, function
<code>.First.sys()</code> in the base package is run. This calls
<code><a href="library.html">require</a></code> to attach the default packages specified by
<code><a href="options.html">options</a>("defaultPackages")</code>. If the methods
package is included, this will have been attached earlier (by function
<code>.OptRequireMethods()</code>) so that namespace initializations such
as those from the user workspace will proceed correctly.

A function <code>.First</code> (and <code><a href="quit.html">.Last</a></code>) can be defined in
appropriate &lsquo;.Rprofile&rsquo; or &lsquo;Rprofile.site&rsquo; files or have
been saved in &lsquo;.RData&rsquo;. If you want a different set of packages
than the default ones when you start, insert a call to
<code><a href="options.html">options</a></code> in the &lsquo;.Rprofile&rsquo; or &lsquo;Rprofile.site&rsquo;
file. For example, <code>options(defaultPackages = character())</code> will
attach no extra packages on startup (only the base package) (or
set <code>R_DEFAULT_PACKAGES=NULL</code> as an environment variable before
running R). Using <code>options(defaultPackages = "")</code> or
<code>R_DEFAULT_PACKAGES=""</code> enforces the R system default.

On front-ends which support it, the commands history is read from the
file specified by the environment variable R_HISTFILE (default
&lsquo;.Rhistory&rsquo; in the current directory) unless
--no-restore-history or --no-restore was specified.

The command-line option --vanilla implies
--no-site-file, --no-init-file,
--no-environ and (except for <code>R CMD</code>)
--no-restore

<h3>Details</h3>

Note that there are two sorts of files used in startup:
environment files which contain lists of environment variables
to be set, and profile files which contain R code.

Lines in a site or user environment file should be either comment
lines starting with <code>#</code>, or lines of the form
<code><var>name</var>=<var>value</var></code>. The latter sets the environmental
variable <code><var>name</var></code> to <code><var>value</var></code>, overriding an
existing value. If <code><var>value</var></code> contains an expression of the
form <code>${foo-bar}</code>, the value is that of the environmental
variable <code>foo</code> if that exists and is set to a non-empty value,
otherwise <code>bar</code>. (If it is of the form <code>${foo}</code>, the
default is <code>""</code>.) This construction can be nested, so <code>bar</code>
can be of the same form (as in <code>${foo-${bar-blah}}</code>). Note that
the braces are essential: for example <code>$HOME</code> will not be interpreted.

Leading and trailing white space in <code><var>value</var></code> are stripped.
<code><var>value</var></code> is then processed in a similar way to a Unix shell:
in particular the outermost level of (single or double) quotes is
stripped, and backslashes are removed except inside quotes.

On systems with sub-architectures (mainly Windows), the
files &lsquo;Renviron.site&rsquo; and &lsquo;Rprofile.site&rsquo; are looked for
first in architecture-specific directories,
e.g. &lsquo;<var><a href="Rhome.html">R_HOME</a></var>/etc/i386/Renviron.site&rsquo;.
And e.g. &lsquo;.Renviron.i386&rsquo; will be used in preference
to &lsquo;.Renviron&rsquo;.

It is not intended that there be interaction with the user during
startup code. Attempting to do so can crash the R process.

On Unix versions of R there is also a file
&lsquo;<var><a href="Rhome.html">R_HOME</a></var>/etc/Renviron&rsquo; which is read very early in
the start-up processing. It contains environment variables set by R
in the configure process. Values in that file can be overridden in
site or user environment files: do not change
&lsquo;<var><a href="Rhome.html">R_HOME</a></var>/etc/Renviron&rsquo; itself. Note that this is
distinct from &lsquo;<var><a href="Rhome.html">R_HOME</a></var>/etc/Renviron.site&rsquo;.

Command-line options may well not apply to alternative front-ends:
they do not apply to <code>R.app</code> on macOS.

<code>R CMD check</code> and <code>R CMD build</code> do not always read the
standard startup files, but they do always read specific
Renviron files. The location of these can be controlled by the
environment variables R_CHECK_ENVIRON and R_BUILD_ENVIRON.
If these are set their value is used as the path for the
Renviron file; otherwise, files &lsquo;~/.R/check.Renviron&rsquo; or
&lsquo;~/.R/build.Renviron&rsquo; or sub-architecture-specific versions are
employed.

If you want &lsquo;~/.Renviron&rsquo; or &lsquo;~/.Rprofile&rsquo; to be ignored by
child R processes (such as those run by <code>R CMD check</code> and
<code>R CMD build</code>), set the appropriate environment variable
R_ENVIRON_USER or R_PROFILE_USER to (if possible, which it
is not on Windows) <code>""</code> or to the name of a non-existent file.

For the definition of the &lsquo;home&rsquo; directory on Windows see the
&lsquo;rw-FAQ&rsquo; Q2.14. It can be found from a running R by
<code>Sys.getenv("R_USER")</code>.

<code><a href="quit.html">.Last</a></code> for final actions at the close of an R session.
<code><a href="commandArgs.html">commandArgs</a></code> for accessing the command line arguments.

There are examples of using startup files to set defaults for graphics
devices in the help for
<code><a href="../../grDevices/html/x11.html">X11</a></code> and <code><a href="../../grDevices/html/quartz.html">quartz</a></code>.

An Introduction to R for more command-line options: those
affecting memory management are covered in the help file for
<a href="Memory.html">Memory</a>.

<code><a href="readRenviron.html">readRenviron</a></code> to read &lsquo;.Renviron&rsquo; files.

For profiling code, see <code><a href="../../utils/html/Rprof.html">Rprof</a></code>.

<h3>Examples</h3>

<pre>
## Not run: 
## Example ~/.Renviron on Unix
R_LIBS=~/R/library
PAGER=/usr/local/bin/less

## Example .Renviron on Windows
R_LIBS=C:/R/library
MY_TCLTK="c:/Program Files/Tcl/bin"

## Example of setting R_DEFAULT_PACKAGES (from R CMD check)
R_DEFAULT_PACKAGES='utils,grDevices,graphics,stats'
# this loads the packages in the order given, so they appear on
# the search path in reverse order.

## Example of .Rprofile
options(width=65, digits=5)
options(show.signif.stars=FALSE)
setHook(packageEvent("grDevices", "onLoad"),
        function(...) grDevices::ps.options(horizontal=FALSE))
set.seed(1234)
.First &lt;- function() cat("\n   Welcome to R!\n\n")
.Last &lt;- function()  cat("\n   Goodbye!\n\n")

## Example of Rprofile.site
local({
  # add MASS to the default packages, set a CRAN mirror
  old &lt;- getOption("defaultPackages"); r &lt;- getOption("repos")
  r["CRAN"] &lt;- "http://my.local.cran"
  options(defaultPackages = c(old, "MASS"), repos = r)
  ## (for Unix terminal users) set the width from COLUMNS if set
  cols &lt;- Sys.getenv("COLUMNS")
  if(nzchar(cols)) options(width = as.integer(cols))
  # interactive sessions get a fortune cookie (needs fortunes package)
  if (interactive())
    fortunes::fortune()
})

## if .Renviron contains
FOOBAR="coo\bar"doh\ex"abc\"def'"

## then we get
# &gt; cat(Sys.getenv("FOOBAR"), "\n")
# coo\bardoh\exabc"def'

## End(Not run)</pre>

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