> But when you do something like
> cmd1 | cmd2 |[2] cmd3
> you get cmd1's stdout piped to cmd2's stdin; but my confusion begins
> here: is it cmd1's or cmd2's stderr that gets redirected to cmd3's
> stdin? maybe both? my guess is that ...
why guess?
% {echo cmd1 >[1=2]} | {echo cmd2 >[1=2]} | sed 's/^/cmd3: /'
cmd1
cmd2
% {echo cmd1 >[1=2]} | {echo cmd2 >[1=2]} |[2] sed 's/^/cmd3: /'
cmd3: cmd1
cmd3: cmd2
%
not what i expected, but there you have it.
and it makes sense: cmd1 and cmd2 are both
writing to the same stderr, so redirecting it
redirects both.
> how can I redirect cmd1's stderr to cmd3's stdin instead
> of cmd2's? or both?
if you don't care about cmd2's stderr, then you can get rid of it
% {echo cmd1 >[1=2]} | {echo cmd2 >[2]/dev/null} |[2] sed 's/^/cmd3: /'
cmd2
cmd3: cmd1
%
> It's easy to think of more complex cases.
it's easy to think of elephants.
rc does its general-purpose job very well.
if you have special-purpose needs,
as lucio suggests, write a c program.
russ
