If you want to maintain your command history in your shell when using ZSH or Bash do the following:

1. Using your favourite text editor, open .zshrc if you are using Z shell or .bashrc if you are using Bash shell in your home directory.

2. Add the following to the config file of the shell:

    # Large in-session history (up-arrow navigation within the tab)
    HISTSIZE=10000
   
    # Prevent writing history to disk entirely
    SAVEHIST=0
    HISTFILE=/dev/null
   
    # (Optional) Ensure history is NOT shared between tabs or appended across sessions
    unsetopt SHARE_HISTORY
    unsetopt INC_APPEND_HISTORY
    unsetopt APPEND_HISTORY
   

3. Save the file.

4. Reload the config file for the shell by typing source ~/.zshrc or source ~/.bashrc depending on the shell that you are using.

5. Your new settings should have taken effect.