Code:

bash-3.2$ awk 'BEGIN{x=1} /DEFINE SCHEMA/,/\)\;/ {if (NF==2) { $1="t"x" as filler"; print; x++ }}' filename

Code:

BEGIN{x=1}

Assign x with value "1". Then goes through the file.

Code:

/DEFINE SCHEMA/,/\)\;/

If it is within "DEFINE SCHEMA" and ");", it would be true (highlighted in red).

Code:

USING CHARACTER SET UTF8 DEFINE JOB 
 
(
 
DEFINE SCHEMA Flat_File_Schema
(
cntnt_id VARCHAR(10)
);
 
DEFINE OPERATOR o_mload
 TYPE update
 SCHEMA *

The if statement below looks for lines with 2 fields (highlighted in blue) and replaces $1 (field 1 which is cntnt_id) as "tX as filler" where X is then number "1". This would then be incremented by 1 using x++ after. X shall be "2" which will be used for later if we find the next match.

Code:

if (NF==2) { $1="t"x" as filler"; print; x++ }
 
DEFINE SCHEMA Flat_File_Schema
(
cntnt_id VARCHAR(10)
);