如何在CentOS中重置root密码

重启并进入GRUB菜单，按e编辑启动项；2. 在linux或linux16行末添加init=/bin/bash或rd.break；3. 若用rd.break需先chroot /sysroot，再mount -o remount,rw /；4. 执行passwd root设置新密码；5. 若SELinux启用则运行touch /.autorelabel；6. 执行reboot -f重启即可生效，此方法适用于CentOS 7及以上版本且需物理或控制台访问权限。

If you've lost or forgotten the root password on your CentOS system, don't worry — you can reset it by booting into single-user mode. This method works on most CentOS versions (7, 8, Stream, etc.), though the exact steps may vary slightly depending on whether you're using GRUB or GRUB2.

Here’s how to do it:

✅ 1. Reboot and Access GRUB Menu

• Reboot the machine.
• As it boots up, hold down the Shift key (for BIOS) or spam Esc (for UEFI) to bring up the GRUB menu.
• If you see multiple kernel entries, highlight the one you want to boot (usually the top/default one).

✅ 2. Edit the Boot Entry

• Press e to edit the selected boot entry.
• Find the line starting with linux or linux16 (this contains kernel parameters).
• At the end of that line, add:

  init=/bin/bash

  or for newer systems:

  

  rd.break

? Why this works:

• init=/bin/bash bypasses the normal boot process and drops you into a root shell immediately.
• rd.break pauses the boot before the root filesystem is mounted as read-only — useful for SELinux-aware systems (like CentOS 7 ).

✅ 3. Remount Root Filesystem as Writable

Once you're in the shell (either from init=/bin/bash or after rd.break chroot /sysroot), run:

mount -o remount,rw /

⚠️ If you used rd.break, you’ll first need to:

chroot /sysroot

before remounting.

✅ 4. Reset the Root Password

Now just run:

passwd root

Enter your new password twice when prompted.

✅ 5. Update SELinux Context (if applicable)

If SELinux is enabled (default on CentOS), relabel the password file:

touch /.autorelabel

This ensures SELinux doesn’t block login after the password change.

✅ 6. Reboot

Exit the shell:

exec /sbin/init

or just:

reboot -f

Remove any added boot parameters — they were temporary.

? Notes:

• This requires physical or console (e.g., KVM/IPMI) access — it won’t work remotely unless you have out-of-band access.
• In cloud environments (like AWS EC2), use user-data scripts or recovery modes provided by the platform instead.
• Always secure physical access — anyone with console access can reset root this way.

That’s it! You’ve successfully reset the root password without data loss.
Just remember: this is a powerful recovery method — use it responsibly.

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