[R] escape characters in shell commands

From: James Rome <jamesrome_at_gmail.com>
Date: Tue, 24 May 2011 13:40:58 -0400

On a Windows platform I am trying to count the number of lines in a file. In a DOS window, the following works:
C:\Users\jar>findstr /R /N "^" D:\my_dir\my_file | find /C ":" 5317
(it works with double \\ also)

But in R, I need to make this string up with the file name I get from file.choose():
filename = file.choose()
#get the number of lines in the file
# first make a command string with the filename in it cmd = paste('findstr /R /N "^" ', filename, ' | find /C ":"', sep=""') nrec = as.numeric(shell(cmd))

But R puts in escape characters for the ":
> cmd

[1] "findstr /R /N \"^\" D:\\my_dir\\my_file | find /C \":\""

and shell(cmd) does not work properly. And
> nrec=shell('findstr /R /N "^"D:\\my_dir\\my_file | find /C ":"')
> nrec

[1] 0
does not work either.

What am I doing wrong?


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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. Received on Tue 24 May 2011 - 17:44:15 GMT

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