How to write files with Unix end of lines on R for Windows

Question

I have an R script that creates a text file on Windows.

I use both write.table and write functions to write to the file.

I then need to use this file on Unix systems, but the file has Windows end of line characters (^M).

Is it possible to write files with R on Windows that have Unix end of line characters?

Edit

Here is a reproducible example:

output.file <- file.path("./test.txt")

x <- c(1,2,3,4)
y <- c(5,6,7,8)
my.df <- data.frame(x, y)
my.df[] <- lapply(my.df, sprintf, fmt = "%14.7E")

write("First line", file = output.file)
write("Second line", file = output.file, append = TRUE)
write.table(my.df,
            row.names = FALSE,
            col.names = FALSE,
            file = output.file,
            quote = FALSE,
            append = TRUE,
            sep = "")

And the result, as seen by NotePad++:

Answer 1

As stated in help(write.table):

To write a Unix-style file on Windows, use a binary connection e.g. file = file("filename", "wb").

In your example, just change first line to open a "wb" connection and close file at the end:

output.file <- file("./test.txt", "wb")

x <- c(1,2,3,4)
y <- c(5,6,7,8)
my.df <- data.frame(x, y)
my.df[] <- lapply(my.df, sprintf, fmt = "%14.7E")

write("First line", file = output.file)
write("Second line", file = output.file, append = TRUE)
write.table(my.df,
            row.names = FALSE,
            col.names = FALSE,
            file = output.file,
            quote = FALSE,
            append = TRUE,
            sep = "")

close(output.file)

Answer 2

unix type line endings can be achieved by using wb write|binary mode in file connections.

This quote from Rnews article may be helpful: Ripley, B. D. (2001) Connections. R News, 1/1, 16–7.

Text vs binary There is a distinction between text mode and binary mode connections. The intention is that text-based functions like scan and cat should use text mode connections, and binary mode is used with readBin and writeBin. This distinction is not yet consistently enforced, and the main underlying difference is whether files are opened in text or binary mode (where that matters). It now looks as if opening all files in binary mode and managing the translation of line endings internally in R will lead to fewer surprises. Already reading from a connection in text mode translates lines endings from Unix (LF), DOS/Windows (CRLF) and Macintosh (CR) formats (and from all connections, not just files).

# setup file connection
con <- file( output.file )

# open connection
if( !isOpen(con = con, rw = "wb") ) { open( con, open = "wb" ) }

# write contents
write( x = paste( colnames(my.df), collapse = "\t" ), file = con )
for( i in 1:nrow( my.df )){
  write(paste( my.df[i, ], collapse = "\t" ), file = con )
}
close( con )  # close and destroy a connection

# verify file contents
read.table(output.file, header = TRUE, sep = "\t")
#   x y
# 1 1 5
# 2 2 6
# 3 3 7
# 4 4 8