Output error/warning log (txt file) when running R script under command line

Question

If I run R script under command line (actually I run that from calling in VBA), how can I output any error/warning messages to a txt file?

How about yourprogram.exe > anoutputfile.txt ? Although that captures everything. On nix you could direct stderr, not sure about Win. See stackoverflow.com/questions/1109017/… — Pete855217
– Pete855217, Commented Jul 26, 2012 at 9:20
Thank you. I tried to search in web on how to use sink in R but a bit confused on how to output error/warning message in my case. Would you mind give me a quick example on how to do that? Thank you again. — Joyce
– Joyce, Commented Jul 26, 2012 at 9:33
I roughly know how sink() works, but I can only output variables to the output txt file, how to output error message? — Joyce
– Joyce, Commented Jul 26, 2012 at 9:59

Jthorpe · Accepted Answer · 2017-04-28 18:32:42Z

44

You can use sink() to divert messages as well as warnings to a file. The trick is to set the argument type="message":

Here is an example adapted from the help for ?sink:

setwd(tempdir())

## capture messages and errors to a file.
zz <- file("all.Rout", open="wt")
sink(zz, type="message")

try(log("a"))

## reset message sink and close the file connection
sink(type="message")
close(zz)

## Display the log file
readLines("all.Rout")
[1] "Error in log(\"a\") : Non-numeric argument to mathematical function"

edited Apr 28, 2017 at 18:32

Jthorpe

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answered Jul 26, 2012 at 10:11

Andrie

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2 Comments

Joyce Over a year ago

However, how can I close the connection with the log file? I tried sink(), but when I want to delete the log file, I cannot delete that, as seems there is still connection. Only after I closed my R, I can delete that. How should I close the connection?

Jthorpe Over a year ago

This is because in the original answer, sink was not terminated with type="message" and the connection was not closed. (Fixed in the updated answer)

Jean-François Fabre · Accepted Answer · 2019-05-04 13:50:49Z

21

To close the connection with the log file you have to use sink(type="message") instead of sink() and then close(zz).

edited May 4, 2019 at 13:50

Jean-François Fabre♦

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answered Jun 24, 2014 at 16:22

André le Blond

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