shell - escape character "\" not working in awk with $ -

below sample data:

"udbpem1 "."histogrambin_@@@@@002__udbdi02$"  "udbpem1 "."histogrambin_@@@@@002__udbdi02$"

place in tt file, want replace "histogrambin_@@@@@002__udbdi02$" "histogrambin_@@@@@002__udbdi02$_mig"

i using below below awk command substitution not happening.

awk '/histogrambin_@@@@@002__udbdi02\$/ {sub("'histogrambin_@@@@@002__udbdi02\$'","'histogrambin_@@@@@002__udbdi02\$_mig'")} {print}' tt

please let me know wrong command.

thanks, rakesh

adding further information:

the awk command here used replace object name picked file. $ can anywhere in name, want _mig @ end. actual awk command use in script below:

awk '/"'${tab_name}'"/{if (m==""){sub("'${tab_name}'","'${tab_name}_${tab_ext}'");m=1}}{print}'  filename

i have use "" expand awk use shell variables , want replace first occurrence.

thanks, rakesh

in awk line, quotes not correctly used. do

awk '{sub(/h....\$/, "replacement")}7' file

My