replace lines matching a pattern
 

I have several files in that I need to add the text "N CHAR(1)," How can I accomplish this in linux without having to do it manually. Thanks

HAVE

nullcols
(A "to_number(:A,'9')"
,B CHAR(50)
)

WANT

nullcols
(N CHAR(1)
,A "to_number(:A,'9')"
,B CHAR(50)
)

you need to check the command sed:
sed 's/<search string>/<replace string>/' filename is the syntax, you will need to set nullcols as <search string> and the two lines together as replacement.
see man page of sed for additional possibilities, flags and usage (or look for examples on the net).