# Linux Kernel Module Cheat

### 7.2. Run command at the end of BusyBox init

Use the `--eval-after` option is for you rely on something that BusyBox' init set up for you like `/etc/fstab`:

    ./run --eval-after 'echo asdf;ls /proc;ls /sys;echo qwer'

After the commands run, you are left on an interactive shell.

The above command is basically equivalent to:

    ./run --kernel-cli-after-dash 'lkmc_eval="insmod hello.ko;./linux/poweroff.out;"'

where the `lkmc_eval` option gets evaled by our default rootfs_overlay/etc/init.d/S98 startup script.

Except that `--eval-after` is smarter and uses `base64` encoding.

Alternatively, you can also add the comamdns to run to a new `init.d` entry to run at the end o the BusyBox init:

    cp rootfs_overlay/etc/init.d/S98 rootfs_overlay/etc/init.d/S99.gitignore
    vim rootfs_overlay/etc/init.d/S99.gitignore
    ./build-buildroot
    ./run

and they will be run automatically before the login prompt.

Scripts under `/etc/init.d` are run by `/etc/init.d/rcS`, which gets called by the line `::sysinit:/etc/init.d/rcS` in `/etc/inittab`.