Stripping table name prefixes from SAP DirectLink fieldnames

So if you are using ACL DirectLink to do a full table extraction out of SAP, it will create an ACL Table whose fieldnames are prefixed with %TABLENAME%_, so for example BUKRS from BSAK ends up as BSAK_BUKRS. When you are using DirectLink as an ETL shim to export a flatfile extraction, you sometimes want the native field names instead, without prefixes (Careful: if you have specified a server side join in DirectLink, it will use the tablename prefix to distinguish between the same fieldname in two different tables from the resulting join, for example: BKPF_BUKRS, BSAK_BUKRS. Of course, server side joins are to be avoided when doing this type of dump anyway). From the ACL project, extract the table definition:

BSAK_MANDT     UNICODE     1   6   AS "Accounting: Secondary Index for Vendors (Cleared Items);Client"  
BSAK_BUKRS     UNICODE     7   8   AS "Accounting: Secondary Index for Vendors (Cleared Items);Company Code"  
BSAK_LIFNR     UNICODE    15  20   AS "Accounting: Secondary Index for Vendors (Cleared Items);Account Number of Vendor or Creditor"  
BSAK_UMSKS     UNICODE    35   2   AS "Accounting: Secondary Index for Vendors (Cleared Items);Special G/L Transaction Type"  
BSAK_UMSKZ     UNICODE    37   2   AS "Accounting: Secondary Index for Vendors (Cleared Items);Special G/L Indicator"  
BSAK_AUGDT     DATETIME   39  16   PICTURE "YYYYMMDD" AS "Accounting: Secondary Index for Vendors (Cleared Items);Clearing Date"  
BSAK_AUGBL     UNICODE    55  20   AS "Accounting: Secondary Index for Vendors (Cleared Items);Document Number of the Clearing Document"  
...
etc

$ awk '{print $1}' bsak_all.txt | while read line; do echo "DELETE FIELD " $(echo $line | sed 's/[^_]*_\(.*\)/\1/') " OK" && echo "DEFINE FIELD " $(echo $line | sed 's/[^_]*_\(.*\)/\1/') " COMPUTED " $line && echo; done