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
R_ENVIRON; if this is unset,
R_HOME/etc/Renviron.site is used (if it exists,
which it does not in a ‘factory-fresh’ installation). The name
of the user file can be specified by the
environment variable; if this is unset, the files searched for are
.Renviron in the current or in the user's home directory (in
that order). See ‘Details’ 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
environment variable (after tilde expansion). If this variable
is unset, the default is
which is used if it exists
(which it does not in a ‘factory-fresh’ installation).
(it contains settings from the installer in a ‘factory-fresh’
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
local 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
R_PROFILE_USER environment variable (and
tilde expansion will be performed). If this is unset, a file
.Rprofile 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.
utils::dump.frames or after explicitly
loading the package concerned.
R then loads a saved image of the user workspace from
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
.First is found on the search path,
it is executed as
.First(). Finally, function
.First.sys() in the base package is run. This calls
require to attach the default packages specified by
options("defaultPackages"). If the methods
package is included, this will have been attached earlier (by function
.OptRequireMethods()) so that namespace initializations such
as those from the user workspace will proceed correctly.
.Last) can be defined in
Rprofile.site files or have
been saved in
.RData. If you want a different set of packages
than the default ones when you start, insert a call to
options in the
file. For example,
options(defaultPackages = character()) will
attach no extra packages on startup (only the base package) (or
R_DEFAULT_PACKAGES=NULL as an environment variable before
running R). Using
options(defaultPackages = "") or
R_DEFAULT_PACKAGES="" enforces the R system default.
On front-ends which support it, the commands history is read from the
file specified by the environment variable
.Rhistory in the current directory) unless
--no-restore-history or --no-restore was specified.
The command-line option --vanilla implies
--no-environ and (except for
Under Windows, it also implies --no-Rconsole, which
prevents loading the