[R] filename of current device

[Andreas Leha]

Hi David,

David Winsemius <dwinsemius at comcast.net> writes:

> On May 14, 2014, at 3:44 PM, Andreas Leha wrote:
>
>> Hi David,
>> 
>> Thank you for following up on that.
>> 
>> David Winsemius <dwinsemius at comcast.net> writes:
>> 
>>> On May 14, 2014, at 3:04 PM, Andreas Leha wrote:
>>> 
>>>> Hi all,
>>>> 
>>>> how do I find out about the filename, the currently open (let's say pdf)
>>>> device is writing to?
>>>> 
>>>> If I find 'dev.cur()' returning 'pdf 3' when I expect 'nulldevice 1' I
>>>> would like to know, which file that pdf device is actually targeting.
>>>> 
>>>> Any help for my poor organization is highly appreciated...
>>>> 
>>> 
>>> Have your read the help file for pdf()? The first argument is the default naming mechanism:
>>> 
>>> file = ifelse(onefile, "Rplots.pdf", "Rplot%03d.pdf")
>>> 
>>> So if you call pdf() then it will write to the working directory with a named constructed from those choices.
>>> 
>> 
>> Sorry for being unclear.  I am aware of that.  My use case is, that
>> apparently, I have called pdf("somefile.pdf") somewhen during a long
>> lasting R session.
>> 
>> I tend to have separate R sessions open in parallel
>> for the project I am working on.  So, I can easily have R session open
>> that run for weeks.
>> 
>> So, when I return to an R session (when I got some additional data, I
>> was asking for, e.g.) after several days, I do not know what that call
>> was.  And for several reasons, the actual call (pdf("somefile.pdf"))
>> might not even be visible in my R session.
>> 
>> In that situation, I would like to know, which is the open file for the
>> current device.
>
> Well, if you acheived success with the pdf() call by executing
> dev.off() then you closed that device. The previous device does leave
> behind a footprint but not the entire name of hte file or the
> contents.
>
> ?dev.prev
>
>> old.dev <-dev.prev()
>> str(old.dev)
>  Named int 5
>  - attr(*, "names")= chr "pdf"
>
>
> If you had not changed working directory you may be able to then look
> at all of the pdf files. You can get information with file,info()
>
> ?file.info
>
>

Thanks for the follow-up.  I take it, there is no 'easy' way in R to
achieve this.

The best solution (on unix systems) that I have come up with is this:
  system(paste("lsof -p", Sys.getpid(), "| grep pdf"))
(which obviously works only before dev.off())

I was hoping for some more reliable way to achieve this, but it'll work
for me.

Thanks again,
Andreas