[R] system2 commands with backslash

[Zev Ross]

Thanks to Henrik and David for responses. Both were right. A small edit 
to my description of the problem (which has now been solved). I said 
that the first version of system2 ( system2("sed -i s/oldword/newword/g 
d:/junk/x/test.tex")) worked fine but in fact it was not working, it 
just wasn't giving me an error.

Both of these work:

system("sed -i 's/oldword\\s/oldword/g' d:/junk/x/test.tex")
system2("sed", args=c("-i", "s/oldword\\s/newword/g", 
"d:/junk/x/test.tex"))

Thanks again,

Zev

On 10/11/2013 1:24 PM, Henrik Bengtsson wrote:
> system2("sed", args=c("-i", "s/oldword\\s/newword/g", "d:/junk/x/test.tex"))
>
> /Henrik
>
> On Fri, Oct 11, 2013 at 8:58 AM, David Winsemius <dwinsemius at comcast.net> wrote:
>> On Oct 10, 2013, at 8:16 AM, Zev Ross wrote:
>>
>>> Hi All,
>>>
>>> I'm trying to edit a file in place using system2 and sed from within R. I can get my command to work unless there is a backslash in the command in which case I'm warned about an "unrecognized escape". So, for example:
>>>
>>> system2("sed -i s/oldword/newword/g d:/junk/x/test.tex") # works fine
>>> system2("sed -i s/oldword\s/newword/g d:/junk/x/test.tex") # does not work in R (the command works on the command line)
>>>
>>> I've experimented with double slashes to escape the \s,
>> Wouldn't you want to double the backslashes instead?
>>
>>> I've tried the "shell" command, I've tried experimenting with shQuote and can't seem to get around the "unrecognized escape" issue.
>>>
>>> By the way, it would be preferable to have a solution that avoided using double backslashes etc because, unfortunately, in my real-world example, I'm actually replacing double slashes and would prefer not to have quadruple slashes etc.
>>>
>>> I'm using Windows 7, 64 bit.
>>>
>>> Zev
>>>
>>> --
>>> Zev Ross
>>> ZevRoss Spatial Analysis
>>> 120 N Aurora, Suite 3A
>>> Ithaca, NY 14850
>>> 607-277-0004 (phone)
>>> zev at zevross.com
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>> David Winsemius
>> Alameda, CA, USA
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.

-- 
Zev Ross
ZevRoss Spatial Analysis
120 N Aurora, Suite 3A
Ithaca, NY 14850
607-277-0004 (phone)
zev at zevross.com