~~ 2021-01-06T22:18:09+01:00

% echo A B C D E | tr ' ' '\n' > BASE
% echo FOO > PLUG
% ed BASE <<( echo /C/ . -1 r PLUG . wq | tr . '\n' )
10
C
PLUG : No such file or directory
?
10
% ed BASE <<( echo /C/ . -1 r PLUG. wq | tr . '\n' )
10
C
4
14
% cat BASE
A
B
FOO
C
D
E
%