Shell Programming and Scripting

$ cat iteration.awk

BEGIN { while((getline <bfile) > 0) D[$1]=1; RS="<"; FS=">" }

$1 == "Iteration_query-def" {   split($2, Q, " ");      if(D[Q[1]]) M=1 }
$1 == "Iteration" {     P=1     }
P { R=R"<"$0 }
$1 == "/Iteration" { if(M) print R;  M=P=R="" }
END { if(M) print R }

$ awk -v bfile="b" -f iteration.awk a.xml

awk ' 
      function dothis(){
			if(f){print s}
			s=f=""
		       }
      FNR==NR{
		gsub(/[[:space:]]+/,x,$1)
		A[$1]=1
		next
             }
           !f{
		split($2,S,/ /)
		gsub(/[[:space:]]+/,x,S[1])
             	f = (S[1] in A)
             }
             {
                s = s ? s ORS $0 : $0
		if(/<\/Iteration>/)
		 { 
			dothis()	
                 }
             }
	  END{ 
		dothis() 
	     } 
      ' FS=">"  fileB fileA