Linux: 3 Ways to Change a Users Default Shell in Linux

 

Changing the Default Shell

There are several reasons for changing a user’s shell in Linux including the following:

  • To block or disable normal user logins in Linux using a nologin shell.
  • Use a shell wrapper script or program to login user commands before they are sent to a shell for execution. Here, you specify the shell wrapper as a user’s login shell.
  • To meet a user’s demands (wants to use a specific shell), especially those with administrative rights.

When creating user account with the useradd or adduser utilities, the --shell flag can be used to specify the name of user’s login shell other than that specified in the respective configuration files.

Let’s first list all available shells on your Linux system, type:

# cat /etc/shells

/bin/sh
/bin/bash
/bin/nologin
/bin/tcsh
/bin/csh
/bin/dash

Before you proceed any further, note that:

  • A user can change their own shell to anything: which, however must be listed in the /etc/shells file.
  • Only root can run a shell not listed in /etc/shells file.
  • If an account has a restricted login shell, then only root can change that user’s shell.

1. usermod Utility

usermod is a utility for modifying a user’s account details, stored in the /etc/passwd file and the -s or --shell option is used to change the user’s login shell.

First check user account information to view their default login shell and then change the shell from /bin/sh to /bin/bash.

# grep userName /etc/passwd
userName:x:1000:1000:userName,,,:/home/userName:/bin/sh

# usermod --shell /bin/bash userName

# grep userName /etc/passwd
userName:x:1000:1000:userName,,,:/home/userName:/bin/bash

2. chsh Utility

chsh is a command line utility for changing a login shell with the -s or --shell option like:

# grep userName /etc/passwd
userName:x:1000:1000:userName,,,:/home/userName:/bin/bash

# chsh --shell /bin/sh userName

# grep userName /etc/passwd
userName:x:1000:1000:userName,,,:/home/userName:/bin/sh

3. Change User Shell in /etc/passwd file

This method, simply open the /etc/passwd file using any text editor and change a specific users shell.

# vim /etc/passwd

Source: 3 Ways to Change a Users Default Shell in Linux