Shell Programming and Scripting

awk -F':' '
        # NR == Total number of records read from all input file.
        # FNR == Total number of records read from current input file.
        # NR == FNR is an idiom used to read first input file data.
        NR == FNR {

        # A is an associative array indexed by 1st field: $1
                A[$1]

        # next directs awk to stop processing current record and skip.
                next
        }

        # ( $8 in A ) means if 8th field in second input file exists in associative array A
        # ! ( $8 in A ) means if above condition is not true.
        !( $8 in A )

' no_x_code_list input_file.csv

head -1 $SORTED_FILE > $WORK_FILE
echo $no_groups | \
tr ' ' '\n' | \
nawk -F":" 'NR == FNR{A[$1];next}!(substr($8,1,5) in A) \
NR > 1 && $2 !~ /^98/' - $SORTED_FILE >> $WORK_FILE

nawk 'BEGIN{ FS = OFS = ":"}           
      NR == FNR{ A[$1]; next}          
      $2 !~ /^98/ &&                   
      !(substr($8, 1, 5) in A){
      {
        if(substr($17, 1, 2) == "RS") {$17 = " "}
      } print } file1 file2 > file3

nawk 'BEGIN{ FS = OFS = ":"}           
      NR == FNR{ A[$1]; next}          
      $2 !~ /^98/ &&                   
      !(substr($8, 1, 5) in A){
      {
        $17 ~ /RS/ {$17 = " "}
      } print } file1 file2 > file3