awk -v RS="@#$j" '{print gsub(/字符串/,"&")}' file

awk '{s+=gsub(/字符串/,"&")}END{print s}' file

$ cat test
select select
select
$ grep -o 'select' test wc -l
3
$ awk -v RS="@#$j" '{print gsub(/select/,"&")}' test
3
$ awk '{s+=gsub(/select/,"&")}END{print s}' test
3
-- The End --