for Anuj@stackoverflow

split_anuj.bash

# Related comments: http://stackoverflow.com/questions/12515584/splitting-large-file-into-small-multiple-files-based-on-the-column-concatenation#comment16849432_12515771
# Related chat: http://chat.stackoverflow.com/rooms/16930/discussion-between-shawn-chin-and-anuj


# the following splits a file into new files that are named based on fields 2, 3 and 5
# The first line of the input file is used as a header for all new files created

sort -k2,3 -k5,5 -t, infile.txt | awk -F, '
FNR == 1 {     # if first line
  header = $0;  # store line as header
}

FNR != 1 {     # NOT first line

  filename = $2"_"$3"_"$5;

  if (filename != prev) {   # new label found
    print header > filename # create new file with header
    prev = filename  # store
  }

  print >> filename  # append current line to file
}
'