bashrc - How can I show only the current directory after the prompt in Ubuntu 10.04

The way my bash prompt is currently configured, it shows the whole path to the current directory. This is annoying when I'm deep inside a directory tree, as the prompt becomes so long that every command wraps into the next line. How do I make it show only the last part of the path?

This is what I have in my .bashrc:

PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '

# If this is an xterm set the title to user@host:dir
case "$TERM" in
xterm*|rxvt*)
    PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD/$HOME/~}\007"'
    ;;
*)
    ;;
esac

Change the \w (lowercase) to \W (uppercase):

PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\W\[\033[00m\]\$ '
                                                                                       ^^
           this one waaaaaay over here ------------------------------------------------+

Have a look at the Bash Prompt HOWTO for lots of fun details. example:

user@host:/usr/local/bin$ echo $PS1
${debian_chroot:+($debian_chroot)}\[\033[01;31m\]\u@\h\[\033[00m\]:\[\033[01;36m\]\w\[\033[00m\]\$ 

user@host:/usr/local/bin$ export PS1='${debian_chroot:+($debian_chroot)}\[\033[01;31m\]\u@\h\[\033[00m\]:\[\033[01;36m\]\W\[\033[00m\]\$ '

user@host:bin$

The PROMPT_COMMAND variable, if set, is a command that gets run before displaying the prompt specified in PS1. In your case, PROMPT_COMMAND runs an echo statement with certain ANSI escape sequences that manipulate the titlebar of an Xterm.

If you suspect your PROMPT_COMMAND is overriding your PS1 prompt, you can unset it and test things out:

$ unset PROMPT_COMMAND

Finally, be sure that you're changing the PS1 definition that actually gets used. Common locations are /etc/bash.bashrc, /etc/profile, ~/.bashrc, ~/.bash_profile, ~/.profile. The system files are generally (but not always) run before the user files.