Postgres 9.5

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with your_table(example) as (values
  ('ksh $sample/wrapper.sh --filename /abc/test/svc_test_abc_card.yaml'))
select lower(
         substring(
           split_part( example
                      ,'filename'
                      ,2) 
           from '[^ ]+'::text))
from your_table;

lower

/abc/test/svc_test_abc_card.yaml

SELECT 1

with your_table(example) as (values
  ('ksh $sample/wrapper.sh --filename /abc/test/svc_test_abc_card.yaml'))
select ltrim(
         lower(
           substring(
             split_part( example
                        ,'filename'
                        ,2) 
             from '[^ ]+'::text))
        ,'/')
from your_table;

ltrim

abc/test/svc_test_abc_card.yaml

SELECT 1

with your_table(example) as (values
  ('ksh $sample/wrapper.sh --filename /abc/test/svc_test_abc_card.yaml'))
select lower(substring(example from 'filename\s+/?([^ ]+)'))
from your_table;

lower

abc/test/svc_test_abc_card.yaml

SELECT 1