Shell Programming and Scripting

dag
wfd

dag
wfd
chire
hcm

chire
hcm

#! /bin/bash
IFS=$'\r\n'
XYZ=($(cat a1))
for row in ${XYZ[@]};
do
sed -i '/"$row"/d' a2 > tmpfile
mv tmpfile a2
done

grep -vxFf a1 a2 > a3

awk 'NR == FNR {A[$0]; next} {if(!($0 in A)) print}' a1 a2 > tmpfile && mv tmpfile a2

#! /bin/bash
IFS=$'\n'
XYZ=($(<a1))
while read -r line
do
  for row in "${XYZ[@]}"
  do
    if [[ "$row" == "$line" ]]; then
      continue 2 
    fi
  done
  printf "%s\n" "$line"
done < a2

#! /bin/bash4
declare -A XYZ

while read -r line
do
  XYZ[$line]=x
done < a1

while read -r line
do
  if [[ ${XYZ[$line]} != x ]]; then
    printf "%s\n" "$line"
  fi
done < a2

for row in ${XYZ[@]};
do
        sed -i "/$row/d" a2
done