Root invalid default shell

Ivan

2/21/24, 5:25 PM

We have a server with ssh enabled, and we have: PermitRootLogin: no, and a user that is not in sudoers file. Another administator set invalid Shell for root so I can't get root access anymore. When I run su command and enter root password it says: su: failed to execute /bin/vash. I think the admin wanted to set bash as default Shell but here is a typo. How can I access root again?

2 + 0

ssh

bash

root

sudo

chsh

Score:1

Ubuntu

Mark

2/21/24, 5:57 PM

From man su:

   -s, --shell=shell
          Run the specified shell instead of the default.

So try:

su root -s /bin/sh

Then run chsh to reset the shell to a valid default

+ 2

Ivan

2/21/24, 5:59 PM

So I wasn't in sudoers file) But I've already fixed that

Ivan

2/21/24, 5:59 PM

Thanks anyway !

Score:0

Ubuntu

Ivan

2/21/24, 5:58 PM

Oh guys I've fixed that))) Here is my solution:

cp /bin/bash ~/vash
export PATH = "$PATH:~"
alias "/bin/vash"="/home/USER/vash"
su

+ 2

steeldriver

2/21/24, 6:56 PM

I'm struggling to see how this can possibly work - how does an alias defined in the unprivileged shell have any effect on how `su` locates `/bin/vash`? and `export PATH = "$PATH:~"` is invalid (for more than one reason) in at least bash/dash/zsh/ksh. Can you check your command history please?

Ivan

2/21/24, 9:16 PM

@steeldriver Hello, My history matches my post. I understand your doubts because I also wonder how it works but it helped me to access root shell (there I ran chsh command and set bash as a default shell). Maybe I'll try to repeat this on a VM.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Root invalid default shell

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