How to Reset Forgotten Root Password in RHEL/CentOS and Fedora

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Ravi Saive

Simple Word a Computer Geek and Linux Guru who loves to share tricks and tips on Internet. Most Of My Servers runs on Open Source Platform called Linux.

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43 Responses

  1. rajesh says:

    More details on this

    Per Oracle instructions to implement Huge Pages I made the following updates and re-booted:
    /etc/security/limits.conf
    * soft memlock 45298482
    * hard memlock 45298482
    /etc/sysctl.conf
    vm.nr_hugepages = 9219 # calculated with Oracle script

    After reboot, the system is operation, but root login authenticates then fails. We can login as oracle. When try to su, get: can not open session.

    I have booted from disk and went in rescue mode to back out the changes. The changes were backed out, but still cannot login as root.

    • Ravi Saive says:

      @rajesh,
      Seems strange problem, sorry I really don’t have any idea…give me some time to find out solution for you..

  2. rajesh says:

    Hi Ravi,

    I am getting a strange issue. I am not able to login to root using a desired password on SSH / Linux terminal

    The screen gets refreshes and again comes to login prompt . on the other hand i have another user as oracle and through that user I am able to login

    What could be the issue? please suggest the solution. I am using RHEL 5.8

  3. rajinikanth says:

    How to reset forgotten root password without booting……………..

  4. Mohsen Haghighat says:

    It is not necessary to execute all of above steps. After pressing Escape and then ‘a’ (append)

    it is sufficient to type 1 after …_DM with one space , like : rd_NO_DM 1

    and then press Enter

    you are root now and can type passwd ….. enjoy !!!!

  5. Hector says:

    thanks for your help this article help me alot

  6. Rajesh Smart says:

    I want to change username rajesh, instead of giving root help me out:)

  7. Rajesh Smart says:

    It is very simple but very useful & thanks a lot:)
    Regards
    Rajesh

  8. kasun says:

    very helpful information. thanx!

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