#!/bin/bash

#constants
CNT=10
SOURCE="file1.txt"
RESULT="file2.txt"

#copy first field to file2.txt from file1.txt
cat $SOURCE > $RESULT
printf "\n" > $RESULT

#iterate $CNT times, and append the modified content into the file1.txt in each time
for((i = 1; i < $CNT; i++ ))
do
   awk -F'|'  '{$2=val; print $1"|"$2"|"$3"|"$4"|"}' val=$i $SOURCE >> $RESULT
   printf "\n" >> $RESULT
done

#exit normally
exit 0

$ cat aj.txt
0|0|1|random TEXT1|
0|0|2|random TEXT2|
0|0|3|random TEXT3|
0|0|4|random TEXT4|

$ for i in `seq 0 4`
> do
> awk 'BEGIN{OFS=FS="|"}{$2+="'"$i"'"}{print}' aj.txt >> aj.mod
> done

$ cat aj.mod
0|0|1|random TEXT1|
0|0|2|random TEXT2|
0|0|3|random TEXT3|
0|0|4|random TEXT4|
0|1|1|random TEXT1|
0|1|2|random TEXT2|
0|1|3|random TEXT3|
0|1|4|random TEXT4|
0|2|1|random TEXT1|
0|2|2|random TEXT2|
0|2|3|random TEXT3|
0|2|4|random TEXT4|
0|3|1|random TEXT1|
0|3|2|random TEXT2|
0|3|3|random TEXT3|
0|3|4|random TEXT4|
0|4|1|random TEXT1|
0|4|2|random TEXT2|
0|4|3|random TEXT3|
0|4|4|random TEXT4|