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nathaneastwood
nathaneastwood

Reputation: 3764

Check if a file is open using Windows command line within R

I am using the shell() command to generate pdf documents from .tex files within a function. This function sometimes gets ran multiple times with adjusted data and so will overwrite the documents. Of course, if the pdf file is open when the .tex file is ran, it generates an error saying it can't run the .tex file. So I want to know whether there are any R or Windows cmd commands which will check whether a file is open or not?

Upvotes: 1

Views: 3696

Answers (2)

Noodles
Noodles

Reputation: 2011

openfiles /query /v|(findstr /i /c:"C:\Users\David Candy\Documents\Super.xls"&&echo File is open||echo File isn't opened)

Output

592   David Candy     1756     EXCEL.EXE            C:\Users\David Candy\Documents\Super.xls
File is open

Findstr returns 0 if found and 1+ if not found or error.

&    seperates commands on a line.

&&    executes this command only if previous command's errorlevel is 0.

||    (not used above) executes this command only if previous command's errorlevel is NOT 0

>    output to a file

>>    append output to a file

<    input from a file

|    output of one command into the input of another command

^    escapes any of the above, including itself, if needed to be passed to a program

"    parameters with spaces must be enclosed in quotes

+ used with copy to concatinate files. E.G. copy file1+file2 newfile

, used with copy to indicate missing parameters. This updates the files modified date. E.G. copy /b file1,,

%variablename% a inbuilt or user set environmental variable

!variablename! a user set environmental variable expanded at execution time, turned with SelLocal EnableDelayedExpansion command

%<number> (%1) the nth command line parameter passed to a batch file. %0 is the batchfile's name.

%* (%*) the entire command line.

%<a letter> or %%<a letter> (%A or %%A) the variable in a for loop. Single % sign at command prompt and double % sign in a batch file.


.
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Upvotes: 1

flodel
flodel

Reputation: 89097

I'm not claiming this as a great solution: it is hacky but maybe it will do. You can make a copy of the file and try to overwrite your original file with it. If it fails, no harm is made. If it succeeds, you'll have modified the file's info (not the contents) but since your end goal is to overwrite it anyway I doubt it will be a huge problem. In either case, you'll be fixed about whether or not the file can be rewritten.

is.writeable <- function(f) {
    tmp <- tempfile()
    file.copy(f, tmp)
    success <- file.copy(tmp, f)
    return(success)
}

Upvotes: 1

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