> `command' > > if (command -v chmod > /dev/null 2>&1) ; then > chmod go-w /foobar > else > echo 'your system is broken' 2>&1 > exit 1 > fi > > its a shell builtin mandated by posix. > > version of busybox is 0.61-1 command is mandated. command -v is optional. Therefore the above snippet might echo 'your system is broken' on a POSIX-compliant system.