How can I pipe stderr, and not stdout?

Question

I have a program that writes information to stdout and stderr, and I need to process the stderr with grep, leaving

Answer 1

In Bash, you can also redirect to a subshell using process substitution:

command > >(stdlog pipe)  2> >(stderr pipe)

For the case at hand:

command 2> >(grep 'something') >/dev/null