lotte% ls -l /bin/^(cp echo) --rwxrwxr-x M 4328 sys sys 63454 Jan 10 2007 /bin/cp --rwxrwxr-x M 4328 sys sys 57592 Jan 10 2007 /bin/echo lotte% bind /bin/echo /bin/cp lotte% cp file1 file2 file1 file2 lotte% ns |grep echo bind /bin/echo /bin/cp lotte% ls -l /bin/^(cp echo) --rwxrwxr-x M 4328 sys sys 57592 Jan 10 2007 /bin/cp --rwxrwxr-x M 4328 sys sys 57592 Jan 10 2007 /bin/echo ns|grep /bin bind /386/bin /bin bind -a /rc/bin /bin bind -a /usr/fgb/bin/rc /bin bind -a /usr/fgb/bin/386 /bin bind -a /usr/inferno/Plan9/386/bin /bin bind /bin/echo /bin/cp

here's bind(2) man page, in case you're interested in learning some 20 year old technology http://plan9.bell-labs.com/magic/man2html?man=bind&sect=...