Resetting Login Password by Changing Kernel Command Line

Summary

One easy way to reset a local login password is to set a shell (e.g. Bash) as the system init via the kernel command line. After boot, the kernel will start that shell instead of the normal init system, letting you run programs such as passwd to change user passwords.

What happens

• The kernel launches your chosen shell as PID 1, giving you an interactive prompt before normal services start.
• You can run utilities (for example passwd) to reset credentials from that environment.

Important caveats

• If you exit or close that shell, the real init is gone and the kernel will usually panic.
• The normal boot flow is bypassed: system services will not start, and mounts or setups normally done by init (including some tmpfs mounts under /proc or /sys) may be missing.
• This is a recovery technique — it alters the system runtime and is not a replacement for normal boot procedures.

Where to change the kernel command line

• On x86-64 desktops/servers you typically edit the boot entry in GRUB at boot time (or update its config).
• On embedded systems, modify the bootloader configuration or the file where the kernel command line is defined for that platform.

Safety & authorization

Only use this method on machines you own or are explicitly authorized to administer. For lost-password recovery on production systems, prefer safer procedures such as booting a trusted rescue image, using vendor-provided recovery tools, or following your organization’s approved recovery workflow.