Permanently switching to zsh in a script, without being root and without being asked for the password

Question

Is there any way to run chsh -s /bin/zsh without being root and without being asked for the password? I want to put it into a non-interactive script that isn't called by root.

Answer 1

If you don't have the permission to change your login shell, you can tell bash (I assume bash is your login shell) to replace itself with zsh. In your ~/.bash_login, add this line:

exec /bin/zsh --login

Answer 2

If your version of chsh requires a password (mine does), you will need to setup sudo with special permissions. You can configure it to allow access to any program without prompting for a password like this:

user   ALL=(ALL) NOPASSWD:/usr/bin/chsh

Where "user" is your username (or prefix with % for a group name). Make sure specify the full path to your chsh. This will not allow the user to run anything ELSE as root (including from a script) but it will allow that one binary to be run as root without a password, thus bypassing the user-password prompt.

Answer 3

Depending on your exact needs, if you want to do this because you’re running a long script and don’t want it to hang in the middle to that question, you can ask for the password upfront and then execute chsh with sudo privileges, reading the password from stdin.

read -p 'What is your password?' sudo_password

# rest of the script here

sudo -S chsh -s '/bin/zsh' "${USER}" <<< "${sudo_password}"

-S causes sudo to read the password from stdin. Be aware of possible security risks with this approach (I haven’t been able to reproduce that, though, and again, depending on your needs this might not be an issue).