c:\@Work\Perl\monks\NorthernFox>type 11107044.csv
CAT_HEADER,SUPPLIER_CODE,CUSTOMER_CODE
CAT_LINE,0001P,ABC12345,20190924,,1,Z,3.36
CAT_LINE,0002P,ABC12345,20190924,,1,Z,3.36
CAT_LINE,0001P,ABC23456,20190924,,1,Z,2.24
CAT_LINE,0002P,ABC23456,20190924,,1,Z,2.24
CAT_LINE,0001P,ABC34567,20190924,,1,Z,2.24
CAT_LINE,0002P,ABC34567,20190924,,1,Z,2.24

c:\@Work\Perl\monks\NorthernFox>head --lines=1 11107044.csv  > headline.csv

c:\@Work\Perl\monks\NorthernFox>tail --lines=+2 11107044.csv | sort -k 2 -  > sortedbody.csv

c:\@Work\Perl\monks\NorthernFox>cat headline.csv sortedbody.csv  > sorted.csv

c:\@Work\Perl\monks\NorthernFox>type sorted.csv
CAT_HEADER,SUPPLIER_CODE,CUSTOMER_CODE
CAT_LINE,0001P,ABC12345,20190924,,1,Z,3.36
CAT_LINE,0001P,ABC23456,20190924,,1,Z,2.24
CAT_LINE,0001P,ABC34567,20190924,,1,Z,2.24
CAT_LINE,0002P,ABC12345,20190924,,1,Z,3.36
CAT_LINE,0002P,ABC23456,20190924,,1,Z,2.24
CAT_LINE,0002P,ABC34567,20190924,,1,Z,2.24