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

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:

• Ubuntu 15.04 fresh install: Can't rename gnome-terminal tabs
• How to change Terminal Title in ubuntu 16.04
• Example 1; Example 2