Shell management

The default shell used by Alpine Linux is the BusyBox variant of the ash shell. This page explains how to use the default shell and various ways to change the default shell in Alpine Linux.

Ash shell

Alpine Linux uses Busybox Ash shell for its default shell. It is a standard POSIX shell derived from Debian Ash variant.

One's ~/.bashrc file (or, alternatively, a different shell alias file) could be considered as a basis, say, for an ~/.ashrc or ~/.config/ash/ashrc file, reviewing it carefully for syntax/cli variants against that of Ash shell.

Tip: Use checkbashisms script to perform basic checks for the presence of bashisms in scripts and help remove them.

Setting alias

When using Ash shell, one can’t set aliases directly in the ~/.profile file. One can set ENV environment variable in ~/.profile file to refer aliases file. This method works for both login and non login shells, but ENV is sourced, only if the shell is interactive. The following steps does not affect existing ~/.profile and uses ~/.config/ash/profile file :

1. First create the file /etc/profile.d/profile.sh as follows:

   Contents of /etc/profile.d/profile.sh

   if [ -f "$HOME/.config/ash/profile" ]; then . "$HOME/.config/ash/profile" fi
2. Next create the file ~/.config/ash/profile as follows:

   Contents of ~/.config/ash/profile

   export ENV="$HOME/.config/ash/ashrc"
3. Now aliases can be added in the file ~/.config/ash/ashrc:

   Contents of ~/.config/ash/ashrc

   alias a=alias alias l='ls -lh'

The following approach uses ~/.profile and works only for login shells:

1. Edit the ~/.profile as follows:

   Contents of ~/.profile

   # Alias if [ -f ~/.ash_aliases ]; then . ~/.ash_aliases fi
2. Edit ~/.ash_aliases file as follows:

   Contents of ~/.ash_aliases

   alias a=alias alias c=clear alias f=file alias g=grep alias l='ls -lh'

Available shells

All popular shells are available in Alpine Linux. Refer to the following list:

• bash
• zsh
• fish

To install any of the above shells, say for eg: bash shell:

# apk add bash bash-completion

Change default shell

There are various ways to change the default shell in Alpine Linux. You can revert back to ash shell at anytime with the same steps.

Note: After performing the below step, you need to log out and login again for these changes to take effect.

By hand

Edit /etc/passwd manually using an editor of your choice. An example line for a user named user is:

Contents of /etc/passwd

... user:x:1000:1000:user:/home/user:/bin/ash ...

Change /bin/ash to point to the path of a shell from /etc/shells. Take care to not delete/mangle the line, as it would make you unable to log in again. The user should be the user you are changing the default login shell for.

Using chsh command

To use chsh command, install the shadow package:

# apk add shadow

And use chsh:

# chsh username

Now enter the path for the shell you want to use (e.g /bin/zsh) and press Enter to confirm this change. The shell should exist in /etc/shells.

See also

• dash Manual
• Ash README
• Ash source code
• POSIX standard
• stackoverflow on ash shell