How can I make sure that the title of a Terminal tab/window is identical to the command I typed

Question

I noticed that for aliases etc the title of a Terminal tab/window often isn't the same as the command I typed. This is sometimes confusing, especially for long-running processes with similar names.

So how can I configure bash/Terminal in a way which ensures that the window title always reflects the command as typed?

Examples:

• When I type python -m SimpleHTTPServer and press Return in a Terminal window, the tab of that Terminal window should show "python -m SimpleHTTPServer" immediately.

• When I type flushdns, which is my alias for sudo killall -HUP mDNSResponder;sudo killall mDNSResponderHelper;sudo dscacheutil -flushcache and press Return in a Terminal window, the tab of that Terminal window should show "flushdns" immediately.

What I tried:

I tried modifying PS4 to run a command. This works, however it also prints a lot of other garbage, like getting the current git branch and other commands I put in my PS1. If there's a way for PS4 to only run scripts and not output anything (not even line breaks) I'm fine with that too as a solution.

I also tried the various options under Preferences > Profiles > Tab, but it does not allow showing the literal command I just entered.

Answer 1

macOS Catalina (10.15) now uses Zsh, which makes this really easy.

Show the currently running / last run command by disabling auto_title and adding a preexec hook:

# File: ~/.zshrc

DISABLE_AUTO_TITLE="true"

preexec() {
    printf "\e]1;${1}\a"
}

Answer 2

Open a Terminal window and go to preferences. Click on Profiles and select Window from the pane, In the Window pane there is an option to show active process name. Check that box and the one under it that says arguments. See image below.