bash - how to find current shell command

When I run a command, I need to set some shell environment variable that holds the current command from inside ".bashrc". Actually I need to update PROMPT_COMMAND whenever a command is run, and I need the whole command line, from where I will pick relevant value.

PROMPT_COMMAND='TITLE=`echo !!`; echo $TITLE;'

I tried using echo !!开发者_StackOverflow中文版 inside .bashrc but this simply gives me !! as title. Any ideas?

If you're trying to update the title of the xterm, you can use a DEBUG trap:

trap 'echo "$BASH_COMMAND"' DEBUG

See this blog post.

not sure exactly what you need, but it should be in here -- try it :)

#!/bin/bash

echo "# arguments called with ---->  ${@}     "
echo "# \$1 ----------------------->  $1       "
echo "# \$2 ----------------------->  $2       "
echo "# path to me --------------->  ${0}     "
echo "# parent path -------------->  ${0%/*}  "
echo "# my name ------------------>  ${0##*/} "

okay - now that you've clarified your question, I'll offer a different answer.

Actually, the value you want isn't available as an environment variable, but how about this:

tail -n 1 $HOME/.bash_history

am I getting warmer? :)

edit:

note, if you want to use this in your PROMPT_COMMAND, what you'll need to do it this:

export PROMPT_COMMAND='history -a; tail -n 1 $HOME/.bash_history'

hope this helps :)