split.sh

#!/bin/bash

datafile=$1
ctr=0;

while read line
do

  # counter to keep track of line number
  ctr=$((ctr + 1))

  # skip header line for processing
  if [[ $ctr -gt 1  ]];
  then
      # create filename using date field present in record
      vdate=${line%% *}
      vday1=${vdate%%/*}
      vday=`printf "%02d" $vday1`     # day with padding 0
      vyear=${vdate##*/}              # year
      vfilename="$2-${vyear}${vday}.txt" # filname in YYYYMM.txt format

      # check if file exists or not then put header record in it
      if [ ! -f $vfilename ]; then
        head -1 $datafile > $vfilename
      fi

      # put the record in that file
      echo "$line" >> $vfilename
  fi

done < $datafile