Thanks, ikegami, you answered my question perfectly. I just wish perl's open ">&" were smarter or more orthogonal about these things. It would also be convenient for some purposes to have a truly transparent mechanism for doing I/O to variables. As is, I suppose it's just possible for some unknown 3rd party code to assume that every perl file handle has an underlying valid file descriptor and to misbehave when given a file handle opened on a variable. For example, since these file handles don't have an OS-level file descriptor, they can't be passed on to spawned children. My particular problem does involve spawned children, so I've chosen to create file handles to real files rather than to variables.

Animator: It's interesting that independently re-directing STDOUT and STDERR to the same variable works properly, to the degree that output is interleaved as expected. I didn't consider trying that because I thought STDOUT and STDERR would step over each other's toes. There must be some magic coordination going on underneath for this to work. Interesting.