Today I tried to switch to another shell.

First I tried fish, and used chsh -s fish to change fish to default. After some time I found it cannot use ~/.bashrc (&& needs to be replaced by and).

Because I prefer to reusing ~/.bashrc, I found zsh which seems an easier one and followed this documentation to switch to zsh.

While I was running sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)", suddenly it asked me to enter Password:. I entered the root password but got PAM: Authentication failure.

Then I tried chsh -s bash and chsh -s zsh, it always asked me for a password and threw PAM: Authentication failure (not system password). I can't figure this out.

  • Check if you have an alias or something with sudo in your .bashrc/.zshrc/.etcrc – Lucas Serafim Mar 1 '19 at 12:10

Thanks to this question on Server Fault, I worked around this by:

Changing /etc/pam.d/chsh: from:

auth       required   pam_shells.so


auth       sufficient   pam_shells.so

Then it doesn't ask for a password anymore. But I think it better to restore chsh settings after switching the shell.

  • 2
    using sed: sudo sed s/required/sufficient/g -i /etc/pam.d/chsh – ospider Jan 15 '19 at 2:28
  • Did unfortunately not work. But I commented that line out, changed the shell and removed the comment, again. So your hint was the right one for me. – Markus Zeller Jun 3 '19 at 6:26
  1. Use which zshto find your zsh location.

    $ which zsh
  2. Add /usr/bin/zsh to /etc/shells

  3. Check in /etc/passwd that your config is /usr/bin/zsh

  4. Run chsh -s /usr/bin/zsh

  • This only works for the normal user, but not for root. Is it a security feature? – Timo Jan 4 '20 at 7:40
  • could you expand on step 3 please, what if it isn't there? – baxx Aug 16 '20 at 12:51

Try adding at bottom of your $HOME/.bashrc

export SHELL=`which sh`

This works for me! if you want you can put a welcome text in your shell, but you must install figlet using:

sudo apt install figlet

And overwrite the previous code at bottom of your $HOME/.bashrc

export SHELL=`which zsh`
figlet 'Your welcome message LIKE FOR ME: Welcome'

An alternate work around –

My /etc/pam.d/chsh file has this section:

# This allows root to change user shell without being
# prompted for a password
auth        sufficient  pam_rootok.so

As the comment suggests, it lets root change the shell without needing to product the password. As such I was able to change my shell (to zsh) by running chsh as root and specifying my user account, eg:

sudo chsh $USER -s $(which zsh)

For those for whom the top two solutions did not work. I've found my solution here: https://askubuntu.com/a/950531/1168898

There is a workaround for gnome-terminal:

  1. Go to EditProfile preferencesTitle and Command.
  2. Check Run a custom command instead of my shell.
  3. Provide bash as the Custom command (or fish, or anything).

Try this:

sudo chsh -s $(which zsh) $(whoami)

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