Correct me if I'm wrong. You want to have the ll alias available inside the container. You can achieve this by:

1. Adding this to the Dockerfile:
   RUN echo "alias ll='ls -alF'" >> /etc/bash.bashrc

If you want to leave the Dockerfile as is:

2. Use the postCreateCommand from vscode (If you don't want to change the dockerfile): "postCreateCommand": "echo alias ll=\\'ls -alF\\' >> /etc/bash.bashrc" This will add the alias directly to the system-wide bashrc file. The alias will be available in all interactive shells started within the container.

   OR

   "postCreateCommand": "echo alias ll=\\'ls -alF\\' >> ~/.bash_aliases" This adds the alias to a separate file specifically for aliases and doesn't require root access in the container. Be aware: You'll need to source the .bash_aliases in .bashrc or else this won't work.(credit: @user317808)

If you run into a "Permission denied" then you can also do this:
"postCreateCommand": "echo alias ll=\\'ls -alF\\' >> /home/vscode/.bashrc" (credit: @Damian)

The settings can be overriden by SHELL variable.

Try to insert :

"containerEnv": {
    "SHELL": "/bin/bash"
}

The official documentation for building with VSCode describes how to set the shell used for initializerCommand, but it seems outdated:

Update your Visual Studio Code settings as documented here: https://code.visualstudio.com/docs/editor/integrated-terminal#_configuration to use Bash on Ubuntu (on Windows) eg: "terminal.integrated.shell.windows": "C:\Windows\System32\bash.exe"

The terminal.integrated.shell.windows setting is no longer valid. I tried using the alternatives with no success:

"terminal.integrated.profiles.windows": {
    "bash": {
        "path": "C:\\Windows\\System32\\bash.exe"
    }
},    
"terminal.integrated.defaultProfile.windows": "bash"

and

"terminal.integrated.automationProfile.windows": {
    "path": "C:\\Windows\\System32\\bash.exe"
},

For both, initializerCommand still uses cmd. The only working solution I came up with is to edit .devcontainer\devcontainer.json manually by adding bash to the command:

"initializeCommand": "bash .devcontainer/build.sh --tag matter-dev-environment:local --version 22"

Although this is not the best way, because you have to change the upstream configuration, it seems to be the only solution for now. Remember to follow the steps in the official documentation, bash is only available for Windows when installing Ubuntu for WSL, and you have to clone the repository using LF instead of CLRF.