Returning Variables in R to Linux Shell

try littler:

warmstrong at linuxsvr2:/tmp$ export MYVALUE=`r -e 'cat(10)'`
warmstrong at linuxsvr2:/tmp$ env|grep MYVALUE
MYVALUE=10
warmstrong at linuxsvr2:/tmp$




On Wed, Apr 22, 2009 at 10:48 AM, Bierbryer, Andrew

If I have an R script that I am executing from a command line in linux,
do you know how I can return the value of the variable in my R script to
the linux environment without writing it to a file in my R script and
then reading the file through cat?





For example, if I had a simple one line R script that just did

? ? ? ? ? ?string <- 'TEST',



when I call

/usr/local/bin/R -no-save < MY_R_FILE,



how can I put the value TEST into a shell variable?



Thanks,



Andrew Bierbryer










? ? ? ?[[alternative HTML version deleted]]

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On Wed, Apr 22, 2009 at 3:48 PM, Bierbryer, Andrew

For example, if I had a simple one line R script that just did

? ? ? ? ? ?string <- 'TEST',



when I call

/usr/local/bin/R -no-save < MY_R_FILE,



how can I put the value TEST into a shell variable?

You can use back-ticks (`) in most shells to capture output. So print
the value you want using R's cat() function, and capture it thus:

$ cat test.R
string <- 'TEST'
cat(string)

$ v=`R --slave --no-save < test.R `
$ echo $v
TEST

bash shell also allows $( ) notation:

$ v=$(R --slave --no-save < test.R )

 note the use of --slave to make R shut up about itself.

Barry

| try littler:
| 
| warmstrong at linuxsvr2:/tmp$ export MYVALUE=`r -e 'cat(10)'`
| warmstrong at linuxsvr2:/tmp$ env|grep MYVALUE
| MYVALUE=10
| warmstrong at linuxsvr2:/tmp$

Thanks to a suggestion by Paul Gilbert, littler supports the 'status'
argument to q() to pass result codes back to the shell --- in bash you can
pick that up via $? as shown here:

edd at ron:~> r -e 'q(status=10)'; echo "Status was $?"
Status was 10
edd at ron:~>

Dirk

Three out of two people have difficulties with fractions.