Bash – Grab the last executed command from history as a string and store in variable in bash

bashcommand historyshell-script

I'm trying to grab the last executed command, with options, and store it as a string to be written to a file. I've tried using fc but that can only give me the next to last command (for me anyways) and I've also tried !!:p which gives the right command when I type it but I can't seem to get it to work in the function itself. Can I accomplish this?

Here's what's going on. arg is what I want the string to be.

#!/bin/bash                                                                     

foo(){
    read HISTNUMVAR < histnum.txt
    TEMPHNV=$(fc -l 0 | grep -o '^[0-9]*');
    if [ $TEMPHNV -ne $HISTNUMVAR ]; then
        arg=$(***last history command here***);
        ./write_arg_to_file.sh $arg;
    fi
    echo $TEMPHNV > histnum.txt;
}

The script does everything else I need it to do besides grab the right history command.

Best Answer

There's probably a cleaner way, but you can get the previous command from history with

prev=$(fc -ln | tail -2 | head -1)

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You can access the just-executed command line with the history built-in. (I have no idea why history 1 prints the just-executed command line but fc -nl -1 prints the previous commmand, as does fc -nl 0.)

PROMPT_COMMAND='echo -en "\033[38;5;2m"; history 1; echo -en "\033[0m\n"'

This prints a number before the command text. Here's a version that removes the number. (It may be incorrect if you go beyond 99999 history lines, I don't know how bash formats the number then.)

prompt_function () {
  local prompt_history="$(history 1)"
  prompt_history=${prompt_history:7}
  echo -En $'\033[38;5;2m'"$prompt_history"$'\033[0m\n'
}
PROMPT_COMMAND=prompt_function

(Note that echo -en ..."$prompt_history"... would expand backslashes in the command line, so I use echo -E and let the shell expansion generate the control characters with $''.).

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Based on the answer to the comment up above, it appears your are overriding TERM in one of your startup scripts. While inside screen, your TERM should be set to 'screen', not 'xterm-256color'.

I would look through your shell startup scripts. ~/.bashrc, /etc/bash/bashrc, and possibly others like ~/.bash_profile and /etc/profile depending on how you have everything set up. If you see any TERM="..." settings, you need to remove those.

Best Answer

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