I have a 4-column data frame named as mytable with hundreds of rows. It looks like
id name count rate
234 uert e@3 erwafrw
You seem confused about the difference between a file and the console output. There is no limitation to the width of lines with write.table, at least not ones you will approach in normal use. You can control the console screen width with options(width=72) and use capture.output(print(mytable)) so the ouput meets whatever unstated width requirements you might have.