Follow up: How to write a Linux virus

Won't it succeed if the interpreter is in /usr/bin like perl for example?

Do not allow direct execution of any binaries on the mounted file system. (Until recently it was possible to run binaries anyway using a command like /lib/ld*.so /mnt/binary. This trick fails since Linux 2.4.25 / 2.6.0.)

For ~/bin to work for trad shell scripts and such, you need the file to be opened for processing by the exec-ed interpreter, in another filesystem.