Comment 22 for bug 1325571

From "Changing your Login Shell"
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The correct way for a user to change his or her shell
is via the chsh command.

chsh stands for change shell,
and does exactly what the name suggests.

Invoke it with no arguments and you will be prompted
for your password, then you will be prompted for your shell.

The file /etc/shells is consulted, and your chosen shell must
be included in there for your change to be accepted. If you
enter the name of a binary which is not contained in
/etc/shells you'll receive and error similar to this: