Change default shell on MSYS2

I just ran into this problem. To get zsh running I did this:

• Installed MSYS2
• From the directory I installed MSYS2, I ran mingw32_shell.bat
• Upgraded all installed packages by running pacman -Syu
• Installed zsh and curl by running pacman -Sy zsh curl
• Closed the MinGW shell by running exit - I did not run zsh immediately after installation.
• Edited msys2_shell.bat, mingw32_shell.bat, and mingw64_shell.bat and changed every instance of: start %WD%mintty -i /msys2.ico /usr/bin/bash --login %* to: start %WD%mintty -i /msys2.ico /usr/bin/zsh --login %* (on line 39 as of 2015-09-23)
• Ran mingw32_shell.bat
• At the zsh configuration menu I select 0 to create the .zshrc file.

When configuration finished I saw:

zsh-newuser-install:1119: command not found: rm

Which didn't look right... since rm should never net be found on a healthy *nix system (I'm guessing it's a bug with MSYS2's zsh package), but everything ran fine after that.

The first time I tried this when I ran opened up a batch file to create a new session I received an error about zsh's memory space already being occupied. To fix this I closed all open MinTTY windows and ran the autorebase.bat file in the MSYS2 installation directory. Everything worked after that.

Then I installed oh-my-zsh. Using:

sh -c "$(curl -fsSL https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"

I ran into this using the newer msys2-launcher, that provides .exe launchers rather than batch files.

For this, it was simply a matter of changing the .ini files alongside the launchers inside the Msys2 root directory (for a 64-bit installation, it might contain msys2.ini, mingw32.ini and mingw64.ini). For each of those ini files, add a line to set the shell:

SHELL=/usr/bin/zsh

Edit /etc/nsswitch.conf, and change the setting below:

db_shell: /bin/zsh

When changing default shell is not supported, one way to use the shell you like is to start it immediately when the default shell starts.

For example, just write zsh to ~/.bashrc, and when bash starts, it will run zsh for you. How ever a stray bash process is left running, and you have to quit shell twice when logging out. To make it better, write exec zsh instead of zsh, this way, the bash process is completely replaced with a zsh process.

This method is not perfect but it should work well in most cases. Compared to changing hard-coded values, it may cause less compatibility issues.

It is first mentioned in this answer on StackOverflow.

My install did not have the files mentioned in the accepted answer (msys2_shell.bat, mingw32_shell.bat, and mingw64_shell.bat).

Instead my Win10 system install of MSYS2 (using the installer file msys2-x86_64-20161025.exe) has a single file, msys2_shell.cmd with the line:

set "LOGINSHELL=bash"

I changed bash to zsh. Seems to work so far.