Message-ID: <49F82663.7040905@idi.ntnu.no>
Date: 2009-04-29T10:05:23Z
From: Wacek Kusnierczyk
Subject: send command to other program
In-Reply-To: <49F81FC9.2080409@bitwrit.com.au>
Jim Lemon wrote:
> thoeb wrote:
>> Hello,
>> does anybody know about how to "send" a command or a text line from R to
>> another program? I have written a script in which several
>> calculations are
>> made and outputfiles (csv) are generated. Afterwards I open another
>> program
>> (Fortran) via shell.exec. This program asks for the names if the output
>> files and it would be quite practically if it could just adopt the file
>> names from the r script.
>>
> Hi Tamara,
> If the succeeding program can read the name of the input file via the
> command line arguments, like:
>
> myfortranprogram -i myfile.csv
>
> you can include the arguments in the shell call. Alternatively, you
> could have R write a shell script that would execute the program with
> the appropriate arguments, then call the shell script from R. Of
> course if your program has to have keyboard input for the filename,
> you would have to resort to magic like writing the filename into the
> keystroke buffer.
if your r code produces just the file names, each on a separate line,
and the other program takes file names from the args list with no
particular option needed to specify them, you might try:
r <your r script> | xargs <your program>
<your program> $(r <your r script>)
as in
# dummy files and scripts
echo "foo" > foo
echo "bar" > bar
echo "cat(paste(c('foo', 'bar'), '\n', collapse=''))" > script.r
echo 'for f in "$@"; do echo "input: $f"; done' > program
chmod 755 program
r script.r | xargs ./program
./program $(r script.r)
you may need to adapt the pattern to a shell other than bash.
vQ