How to make the top bar of my terminal say what command is running?

command-line

I often run commands in parallel that take a long time to finish and sometimes I lose track of what is running where since they output basically the same sort of information on screen.

Do you know of any way to find out what command is running in what terminal?

Taken from Bash - Update terminal title by running a second command · U&L and slightly changed:

trap 'echo -ne "\033]2;$(history 1 | sed "s/^[0-9 ]* \+//")\007"' DEBUG

This (ab)uses the DEBUG signal as a trigger to update the title with the last entry from your history, i.e. the last command you executed, via an XTerm Control Sequence. Add the line to your ~/.bashrc to have the feature enabled in every new terminal window.

To print other command output alongside in the title, say the current directory with pwd followed by ": " and the currently running command, I recommend using printf as follows:

trap 'echo -ne "\033]2;$(printf "%s: %s" "$(pwd)" "$(history 1 | sed "s/^[0-9 ]* \+//")")\007"' DEBUG

Some terminal emulators allow you to specify a dynamic title and even give you the command name as an option so that you don't even need to fiddle around – I searched and found it in yakuake's profile settings.

The terminal window title could be changed by changing of the value of the variable $PS1 - the primary prompt string.^{[1] [2]}. We could combine this solution with the idea of using the history command from the Dessert's answer.

Approach 1: Update the value of $PS1 automatically. (Update)

Add the following lines to the bottom of the file ~/.bashrc:

# Change the terminal window title, based on the last executed command
rtitle() {
        # If the variable $PS1_bak is unset,
        # then store the original value of $PS1 in $PS1_bak and chang $PS1
        # else restore the value of $PS1 and unset @PS1_bak
        if [ -z "${PS1_bak}" ]; then
                PS1_bak=$PS1
                PS1+='\e]2;$(history 1 | sed "s/^[0-9 ]* \+//")\a'
        else
                PS1=$PS1_bak
                unset PS1_bak
        fi
};
export -f rtitle        # Export the function to be accessible in sub shells
#rtitle                 # Uncomment this line to change the default behaviour

Then source ~/.bashrc or just open a new terminal and use the function in this way:

Execute rtitle to start changing the terminal window title automatically, based on the last executed command.
Execute rtitle once again to return to the default behaviour.

Approach 2: Update the value of $PS1 manually. (Initial answer)

Add the following lines to the bottom of the file ~/.bashrc:

set-title() {                                                                                 # Set a title of the current terminal window
        [[ -z ${@} ]] && TITLE="$(history 2 | head -1 | sed "s/^[0-9 ]* \+//")" || TITLE="$@" # If the title is not provided use the previous command
        [[ -z ${PS_ORIGINAL} ]] && PS_ORIGINAL="${PS1}" || PS_ORIGINAL="${PS_ORIGINAL}"       # Use the original value of PS1 for each future change
        PS1="${PS_ORIGINAL}"'\e]2;'"$TITLE"'\a'                                               # Change the prompt (the value of PS1)
}; export -f set-title

Then source ~/.bashrc or just open a new terminal and use the function in this way:

set-title <something> will change the terminal window title to <something>.
set-title without argument will change the terminal window title to the previous command.

References and examples: