There are some .txt files that have the same columns and different rows. My question is how to convert these .txt files into a new .txt file.In other words, how to add all .txt files rows into a new .txt file.
If they are all in the same format, i.e. same number of columns (same header), you can loop through the files, read them with read.table(), and write them to your destination file with write.table() using the "append=TRUE" attribute.
You will find such answers on stack exchange/ stack overflow