How do I boot with init=/bin/bash ?

How do I boot with init=/bin/bash ? What do I have to do ?

 

Do you mean that you want to boot into single user mode? If so, and assuming you are using grub, you just append a 1 to your grub boot line.

So when you are presented with the grub boot menu, select your choice, then hit 'e' to edit instead of enter.
Then scroll down to the line it displays with 'kernel /boot/kernel-X.Y.Z ....' and again hit 'e' to edit it.
Scroll to the end of the line and append a "1" (no quotes), then ENTER. This tells the kernel to boot into runlevel 1, the single user level.
Finally hit 'b' to boot using this new configuration. Note that this is a temporary change to your grub configuration. Upon next reboot the 1 will not be there and you will be back to the regular options.

Your should now boot into single user mode which should boot no services and present you with just a root prompt (/bin/bash).

Hope this is what you want