-s string

change all letters in string to lowercase. Any other command line options are ignored and tables or files waiting to be read from the standard input are flushed.

-fc

use c as the input field separation character.

-h

do not alter the header row (for tables and lists only).

column ...

change all text to lowercase only in the named column(s).

$ lower -s 'This Is A Fine State Of Affairs!'
this is a fine state of affairs!

$ cat inventory
Item    Amount  Cost    Value   Description
----    ------  ----    -----   --------------
   1         3    50      150   Rubber Gloves
   2       100     5      500   Test Tubes
   3         5    80      400   Clamps

$ lower < inventory
item    amount  cost    value   description
----    ------  ----    -----   --------------
   1         3    50      150   rubber gloves
   2       100     5      500   test tubes
   3         5    80      400   clamps

$ lower -h description < inventory
Item    Amount  Cost    Value   Description
----    ------  ----    -----   --------------
   1         3    50      150   rubber gloves
   2       100     5      500   test tubes
   3         5    80      400   clamps