linux - running system command in R and then writing output to a file

Question

I have R code as below. Below code resides in a file called 'iot.R'. I am executing it in Linux.

I want to print content of variable 'fileinformation' to a file mentioned by file=fileConn... I thought that the 3rd line will solve the issue, but it is not giving the required output :(

   fileinformation = system(paste("file", filenames[1]))
    #print(fileinformation)
    cat(print(fileinformation),"\r\n","\r\n", file=fileConn)

When I run the file, i get below result. It prints to my screen, rather than writing to the file :(

> source('iot.R')
CH7Data_20130401T135010.csv: ASCII text, with CRLF line terminators
[1] 0

--------------------update1

I also tried below command, but didnt get the expected rsult

cat(capture.output(fileinformation),"\r\n","\r\n", file=fileConn)

nicola · Accepted Answer · 2014-10-01T20:30:32.530

You need to set the intern argument to TRUE in your call to system. For instance:

    fileinformation<-system("file cinzia_2.gif",intern=TRUE)
    fileinformation
    #[1] "cinzia_2.gif: GIF image data, version 89a, 640 x 640"

Of course I tried a file on my pc. Setting intern to TRUE the return value of system becomes the console output of the command. Then, when you call cat, you don't need to enclose fileinformation into print, but a simple cat(fileinformation,"\r\n","\r\n", file=fileConn) will suffice.

score 0 · Answer 2 · answered Oct 01 '14 at 19:47

0

Hi Just a comment as I dont have enough rep to comment in the normal way. but cant you use

write.table

to save the output to a file? It may be easier?

answered Oct 01 '14 at 19:47

mattbawn

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i am writing a lot of other data to file=fileConn..aand write.table will create a different table...it wont add to fileConn :( – user2543622 Oct 01 '14 at 19:49
in that case write() instead of print with append=TRUE? – mattbawn Oct 01 '14 at 19:53
something like: write(fileinformation,file=fileConn,append=TRUE)? its hard to comment without reproducible code. – mattbawn Oct 01 '14 at 20:19
the following may also be of use: http://stackoverflow.com/questions/16658866/writing-variables-to-a-file-with-writelines – mattbawn Oct 01 '14 at 20:20
same thing...it didnt help. It printed 0 to the actual file and printed output of the command to the screen – user2543622 Oct 01 '14 at 20:22

linux - running system command in R and then writing output to a file

2 Answers2