UNIX for Dummies Questions & Answers

Combine ----- test.sh
....... ----- result ---- april
.................... ---- may
.................... ---- june
.................... ---- july

bash test.sh

#!/bin/bash
#
#	Script to be placed in "Combine" folder
#	Retrieve files from "Combine/result"
#	Output to "Combine/output"
#
#
#	Vars
#
	FZ=(result/*) 		# all entries of ./result
	ZC=0 			# Z Counter
#
#	Action
#
	[[ -d output ]] || mkdir output

	for Z in "${FZ[@]}"
	do
		THESE="$Z"	# Set '$THESE' to a new single value
				# As we have a new variable to start with
		for I in 1 2 3
		do
			THESE+=" ${FZ[$[ $ZC + $I ]]}"
			str=$(echo "$THESE"|sed s,' ','-',g)
			cat "$THESE"|sort -u > output/${str}.txt
		done

		((ZC++))
	done
#
#	Verify
#
	ls output

Anna|Smith|2013|Testing
Andrew|Smith|2012|data
Mark|Green|2010|system
Tony|Green|2009|Testing

George|White|2010|system
Hanna|Brown|2009|data

Anna|Smith|2013|Testing
Andrew|Smith|2012|data
Hanna|Brown|2009|data
Tony|Green|2009|Testing

Anna|Smith|2013|Testing
Tony|Green|2009|Testing
Hanna|Brown|2009|data

april (or april-april) extension not important
april-may (or visa versa for all)
april-june
april-july
may-june
may-july
june-july
april-may-june
april-may-july
april-june-july
may-june-july
april-may-june-july

#!/bin/bash
#
# cd to Combine folder and call script there. Otherwise put "cd /path/to/Combine" in your script
#
combine_files() {
  local p i
  to=../output/$*
  to=${to// /-}
  [ -f "$to" ] || cat "$@" > "$to"
  if [ $# -gt 2 ]; then
    for((i=0; i<$#; i++))
    do
      p=("$@")
      unset p[i]
      combine_files "${p[@]}"
    done
  fi
}

# cd /path/to/Combine
[ -d output ] || mkdir output
cd result
combine_files *