Eric Sunshine [off-list ref] writes:
These tests all crash and burn with BSD sed (including Mac OS X) since
you're not restricting yourself to BRE (basic regular expressions).
You _could_ request extended regular expressions, which do work on
those platforms, as well as with GNU sed:
sed -nEe "/^(author|summary) /p" ...
An obvious way to avoid any RE is to write it as two separate
statements. As there are repeated invocations of this filtering
in this script, perhaps a helper function can hide this ugliness?