To change the default shell on a Solaris or OpenSolaris system, you can use the chsh command.
To change the default shell for a specific user, run the following command:
chsh -s /path/to/shell username
Replace /path/to/shell with the path to the shell you want to use, and username with the name of the user whose default shell you want to change.
For example, to change the default shell to bash for the user john, you would run:
chsh -s /bin/bash john
To change the default shell for the current user, you can omit the username parameter:
chsh -s /path/to/shell
Note: These commands require root privileges to execute if you are changing the default shell for a user other than the current user.