macos - Set the title of the terminal window to the current directory

How can I get the Terminal.app in OS X to display the current directory in its window or tab title?

I'm using the bash shell.

Answer

Depends on your shell.

This article displays multiple methods.

I personally use zsh which has a convenient precmd() function which is run before each prompt.

    precmd () { print -Pn "\e]2;%n@%M | %~\a" } # title bar prompt

Although the other questions list bash methods, they alias cd. Bash provides an inherent method that chains off just the prompt.

bash

bash supplies a variable PROMPT_COMMAND which contains a command to execute before the prompt. This example (inserted in ~/.bashrc) sets the title to "username@hostname: directory":

 PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD}\007"'

where \033 is the character code for ESC, and \007 for BEL. Note that the quoting is important here: variables are expanded in "...", and not expanded in '...'. So PROMPT_COMMAND is set to an unexpanded value, but the variables inside "..." are expanded when PROMPT_COMMAND is used.

However, PWD produces the full directory path. If we want to use the '~' shorthand we need to embed the escape string in the prompt, which allows us to take advantage of the following prompt expansions provided by the shell:

\u          expands to $USERNAME
\h          expands to hostname up to first '.'
\w          expands to directory, replacing $HOME with '~'
\[...\]     embeds a sequence of non-printing characters

Thus, the following produces a prompt of "bash$ ", and an xterm title of "username@hostname: directory" ...

 case $TERM in
     xterm*)
        PS1="\[\033]0;\u@\h: \w\007\]bash\$ "
        ;;
     *)
        PS1="bash\$ "
        ;;
 esac

Note the use of [...], which tells bash to ignore the non-printing control characters when calculating the width of the prompt. Otherwise line editing commands get confused while placing the cursor.