I wrote: > It remains unclear why you had an intervening shell process when > I didn't, but perhaps that can be chalked up to use of a different > shell?
To provide some data on that: popen() is presumably invoking /bin/sh, which on my box is $ /bin/sh --version GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu) $ rpm -qf /bin/sh bash-4.1.2-48.el6.x86_64 regards, tom lane