# Windows Batch Files for R #

G. Grothendieck

Software and documentation is (c) 2013 GKX Associates Inc. and licensed under [GPL 2.0](http://www.gnu.org/licenses/gpl-2.0.html).

## Introduction ##

This document describes a number of Windows batch, javascript and `.hta` files
that may be used in conjunction with R.  Each is self contained and independent
of the others.  None requires installation - just place on the Windows path or
in current directory.  ^[To display the Windows path enter `path` without
arguments at the Windows `cmd` line.  To display the path to the current
directory enter `cd` without arguments at the Windows `cmd` line.]

`R.bat` and `Rpathset.bat` are alternatives to each other intended to
facilitate the use of R without permanently modifying the Windows
configuration.   They can also be useful on systems with
restricted access to the registry.
`R.bat` uses heuristics to automatically locate `R`, `MiKTeX` and `Rtools`.  In
contrast, `Rpathset.bat` takes a simpler approach of having the user manually
edit the `set` statements in it.  `R.bat` does not require changes when you
install a new version of R.  It will automatically detect this; however,
`Rpathset.bat` will require that the `set` statements be modified
appropriately.  `R.bat help` gives a quick overview and some examples.  Another
way to use `R.bat` is to copy it to `#Rscript.bat` in which case a call to
the new
version can be placed in the first line of any R script to turn it into a
Windows batch file (as described later).

`movedir.bat` and `copydir.bat` are used for moving or copying packages from
one library to another such as when R is upgraded to a new version.

`el.js` runs its arguments in elevated mode (i.e. with Administrator
privileges).

`clip2r.js` copies the current clipboard into a running R instance. It can be
used with `vim` or other text editor.

`find-miktex.hta` displays a popup window showing where it found MiKTeX. 

## R.bat ##

### Purpose ###

The purpose of `R.bat` is to facilitiate the use of R from the Windows `cmd` 
line by eliminating the need to make any system changes.  There is no need to
modify the Windows path or to set any environment variables for standard
configurations of R.  It will automatically locate R (and Rtools and
MiKTeX if installed) and then run `R.exe`, `Rgui.exe` or other command.

Another scenario for which it is useful is when there are only restricted
permissions available such as no ability to write to the registry.
Windows supports 4 sets of environment variables (system, user, volatile,
process) and the first three are stored in the registry but the last
is stored only in the local process.
`R.bat` can work with process environment variables so it can be used in
such situations where there are minimal permissions.

Like all the other utilities here, `R.bat` is a self contained no-install script
with no dependencies so just place it anywhere on your Windows path or in the 
current directory.

### Typical Usage ###

Typical usage of `R.bat` to launch R gui is the following ^[
If `R.exe` were on the Windows path and before `R.bat` then it would
have to be written as follows: `R.bat gui`]:

	R gui


This runs `Rgui.exe`.  If further arguments are specified they are passed on to
`Rgui.exe`.  For example,

	R gui --help

will run: 

	Rgui.exe --help

### Subcommands ###

If the first argument is optionally one of `cd`, `cmd`, `dir`, `gui`, `help`,
`path`, `R`, `script`, `show`, `SetReg`, `tools`, `touch` or the same except
for upper/lower case then that argument is referred to as the subcommand.  

If no subcommand is provided then the default subcommand is derived from the
name of the script.

If the script is named `R.bat` then the subcommand `R` is implied.  If the
script has been renamed then any leading `R` is removed from the name and the
remainder becomes the default subcommand.  For example, if `R.bat` were renamed
`Rgui.bat` then issuing `Rgui` would be the same as running `R gui` .

### Other R Executables ###

Other executable files that come with R (`R.exe`, `Rcmd.exe`, `Rscript.exe`)
can be run in a similar way:

	R --help
	R cmd --help
	R script --help

(`RSetReg.exe` is another executable that comes with R for Windows. It will be 
discussed later.)

### Support Subcommands ###

There are also some support commands:

	R cd
	R dir
	R ls
	R help
	R show

`R cd` changes directory to the `R_ROOT` directory (typically 
`C:\Program Files\R`).

`R dir` displays the contents of that directory in chronological order - oldest
first and most recent last.  `R ls` is the same as `R dir`.

`R show` shows the values of the `R_` environment variables used by `R.bat` .
Below is a list with typical values.  These values are determined by the script
heuristically (or the user can set any before running `R.bat` or 
`R.bat` itself can be customized by setting any of them near top of the script).

	R_ARCH=x64
	R_CMD=RShow
	R_HOME=C:\Program Files\R\R-2.15.3
	R_MIKTEX_PATH=\Program Files (x86)\MiKTeX 2.9\miktex\bin
	R_PATH=C:\Program Files\R\R-2.15.3\bin\x64
	R_REGISTRY=1
	R_ROOT=C:\Program Files\R
	R_TOOLS=C:\Rtools
	R_TOOLS_PATH=C:\Rtools\bin;C:\Rtools\gcc-4.6.3\bin;
	R_TOOLS_VERSION=3.0.0.1927
	R_VER=R-2.15.3

`R_PATH`, `R_MIKTEX_PATH` and `R_TOOLS_PATH` are the paths to the directories
holding the `R`, `MiKTeX` and `Rtools` binaries (i.e. `.exe` files).  

`R_CMD` indicates the subcommand or if no subcommand specified then it is
derived from the name of the script.  For example if the script were renamed
`Rgui.bat` then if no subcommand were specified it would default to `gui`.

`R_ROOT` is the directory holding all the R installations. `R_HOME` is the
directory of the particular R installation.  `R_HOME` is made up of `R_ROOT`
and `R_VER` so that `R_VER` represents the directory that holds the particular
R version used.  `R_ARCH` is `i386` or `x64` for 32 bit or 64 bit R
respectively.  It can also be specified as `32` or `64` in which case it will
be translated automatically.  See the `R show` output above for examples of
values for these variables.

### Path Setting Subcommands ###

The command 

	R path

adds `R_PATH`, `R_MIKTEX_PATH` and `R_TOOLS` to the Windows path for the
current `cmd` line session.  No other `cmd` line sessions are affected and
there are no permanent changes to the system.  Once this is run 
the R binaries will be on the path so they can be accessed directly without
`R.bat` within the same Windows cmd line session.

This mode of operation has the advantage that startup will be slightly faster
since  `R.bat` will not have to run each time that `R` is started. ^[On a 
1.9 GHz Windows 8 machine `R.bat show` runs in 0.75 seconds.]

Note that if both `R.bat` and `R.exe` exist on the Windows path then the first
on the path will be called if one uses:

	R ...arguments...

thus one may wish to enter `R.bat` or `R.exe` rather than just `R` for clarity. 

Alternately, rename `R.bat` to `Rpath.bat` in which case the command `R path`
becomes just `Rpath` and `R` becomes unambiguous.

(An alternative to `R path` is the `Rpathset.bat` utility which will be 
described later.)

The command

	R tools

is similar to `R path` except only `R_TOOLS_PATH` and `R_MIKTEX_PATH` are
added to the path (but not `R_PATH`).  This might be useful if you need to use
those utilities without R.


### Selecting R Version ###

For R installations using the standard locations and not specifying any of the
R_ environment variables the registry will determine which version of R is used
(assuming `R_REGISTRY` is not `0`).  If R is not found in the registry or if
`R_REGISTRY` is `0` then the R
installation in `R_ROOT` which has the most recent date will be used.

If we enter this at the `cmd` line:

	set R_VER=R-2.14.0

then for the remainder of this `cmd` line session that version will be used.
If one wishes to use two different R versions at once we could spawn a new `cmd`
line session:

	start

and then enter the same set command into the new window.  Now any use of R in
the original window will use the default version whereas in the new `cmd` line
window it will use the specified version.

One can change the registry entry permanently to refer to a particlar version
like this:

	cmd /c set R_VER=R-2.14.0 ^& R SetReg

This requires Administrator privileges. If not already running as 
Administrator a window will pop up requesting permission to proceed.

If the registry is empty or `R_REGISTRY=0` then the default version is not
determined by the registry but is
determined by which R install directory is the most recent.  To make a
particular R install directory the most recent run the following in a `cmd`
line session with Administrator privileges:

	R dir
	el cmd /c set R_VER=R-2.14.0 ^& R touch

The value of `R_VER` in the above line must be one of the directories listed 
by `R dir`.  The `el.js` command used in the above code comes with these batch 
files and provides one way to elevate commands to have Administrator 
privileges.

Note that `R SetReg` and `R touch` make permanent changes to the system
(namely installing or uninstalling the R key and updating the date on a
particular R directory, respectively) but the other subcommands make no
permanent changes.

### Heuristic to Locate R ###

1. If `.\Rgui.exe` exists use implied `R_PATH` and skip remaining points.

2. If `.\{x64,i386}\Rgui.exe` or `.\bin\{x64,i386}\Rgui.exe` exists use implied
`R_HOME`.

3. If `R_HOME` defined then derive any of `R_ROOT` and `R_VER` that are not
already defined.

4. If `R_PATH` defined then derive any of `R_ROOT`, `R_HOME`, `R_VER` and 
`R_ARCH` that are not already defined.

5. If `R_REGISTRY=1` and R found in registry derive any of `R_HOME`, `R_ROOT` 
and `R_VER` that are not already defined.

6. If R_ROOT not defined try `%ProgramFiles%\R\*`, `%ProgramFiles(x86)%\R\*`
    and then `%SystemRoot%\R` else error.

7. If `R_VER` not defined use last directory in `cd %R_ROOT% & dir /od`.

8. if `R_ARCH` not defined try `%R_ROOT%\%R_VER%\bin\x64\Rgui.exe` and then
    `%R_ROOT%\%R_VER%\bin\i386\Rgui.exe`

9. If `R_ROOT`, `R_VER` and `R_ARCH` defined skip remaining points.

10. If `Rgui.exe` found on `PATH` use implied `R_PATH`.

## #Rscript.bat ##

This is not a separate batch file but is yet another way to call `R.bat`.  
Its purpose is to turn an R script into a Windows batch file.  

1.  Copy `R.bat` to a file with the name `#Rscript.bat` like this 
(from the Windows cmd line):

	copy R.bat #Rscript.bat

2. Ensure that `#Rscript.bat` is on your windows path.  Then we can turn an
R script into a `.bat` file by 
(a) giving the R script a `.bat` extension and 
(b) putting this line as the 
first line in the script: `#Rscript %0 %*`

This makes the script both a Windows batch file and an R script at the same
time. When run as a batch file it will invoke `#Rscript.bat` which in turn
will self call the script as an R script.  (It would also be possible to
run the script directly as an R script.  In that case the #Rscript line would
be ignored since it would be regarded as a comment by R.)

For example, if we have a file `test.bat` with the following two lines:

	#Rscript %0 %*
	print(pi)

then we can invoke it from the Windows cmd line like this:

	test

## #Rscript2.bat ##

This batch file is used in exactly the same manner as #Rscript.bat .  The only
difference is that unlike #Rscript.bat which automatically finds R with this
script the user must edit it to indicate where R is located.  Although this
involves an extra installation step in return the script is very simple so
its less likely to go wrong and if something does go wrong then its relatively
simple to fix since the script itself is simple.

If you have a 64 bit system then the only part that needs to be changed is
changing the definition of R_HOME to point to your version of R.  If you
have a 32 bit system then you will also have to modify the definition of
R_ARCH on the appropriate line.  

There is more information on this in the comments at the top of the script.

## Rpathset.bat ##

The command 

	Rpathset

adds `R_PATH`, `R_MIKTEX_PATH` and `R_TOOLS` to the Windows path for the
current `cmd` line session.  No other `cmd` line sessions are affected and
there are no permanent changes to the system.  Once this is run 
the R binaries will be on the path so they can be accessed directly without
`R.bat` .   

`Rpathset` is an alternative to 

	R path 

but unlike `R.bat`, `Rpathset.bat` does not have any automatic heuristics.
Instead, it requires that the user manually set the relevant variables in its
source.  Running `Rpathset.bat` then sets the path accordingly and from then on
in the session one can access `Rgui.exe`, etc. on the path.  Although
`Rpathset.bat` involves manual editing it does have the advantage that as a
consequence it is very simple -- not much more than a collection of Windows
batch set commands. This makes it easy to customize, less fragile to 
changes in the install procedures of `R` itself and is also more liklely to
work on untested Windows configurations.

`Rpathset.bat` might be used like this:

	Rpathset
	Rgui

where `Rgui` is now directly accessing `Rgui.exe` as `Rpathset.bat` has added
`R_PATH` to the Windows path.

The set statements are documented in the source of the `Rpathset.bat` file 
itself.

## movedir.bat and copydir.bat ##

`movedir.bat` and `copydir.bat` move or copy the packages from one library to
another.  If used to transfer packages from one version of R to another it is
recommended that the user run `upgrade.packages()` in the target.  For example,
assuming the default location for the user libraries:

	cd %userprofile%\Documents\win-library
	copydir 2.15\library 3.0\library

	R.bat gui 
	... now enter update.packages(checkBuilt=TRUE) into R...

(The `checkBuilt=TRUE` argument forces a rebuild and is normally not required
when upgrading to another version that differs only in the minor version
number, e.g. from 2.15.2 to 2.15.3.)

`movedir.bat` and `copydir.bat` will not overwrite any existing package in the 
target library so they are particularly safe to use.  (If you do wish to 
overwrite such packages delete them from the target first using the Windows
`del` command.)


## el.js ##

`el.js` runs its arguments elevated (i.e. with Administrator privileges).  For example,

	el R touch

The user will be prompted to allow elevation to proceed.

## clip2r.js ##

This program writes the clipboard into the running R session.  It can be used
with `vim` or other editor.  See the source for additional instructions.

## find-mixtex.hta ##

This program displays a window showing where MiKTeX was found. It uses the
MiKTeX API. This API is not used by `R.bat` .  Instead `R.bat` just looks in
common places.  (Using this API may be incorporated into the `R.bat` heuristic 
in the future.)

## make-batchfiles-pdf.bat ##

This batch file creates a pdf of this documentation from the markdown file
`batchfiles.md` .  `pandoc` must be installed for this to run.  `pandoc` can be
found [here](https://code.google.com/p/pandoc/downloads/list).  It is run
without arguments:

	make-batchfiles-pdf

