187

For some reason, occasionally, an uppercase “M” appears at the right side of the window name, so the window name looks like this:

1:bash*M

I'm pretty sure is because I'm pressing some combination that causes this. What is it and what does it means?

Giacomo1968
  • 58,727
André Wagner
  • 2,003

2 Answers2

219

From tmux(1) - STATUS LINE:

Symbol Meaning
<...snip...>
M      The window contains the marked pane.
<...snip...>

From tmux(1) - DEFAULT KEY BINDINGS:

The default command key bindings are:
<...snip...>
m    Mark the current pane (see select-pane -m).
<...snip...>

So that means you've pressed C-b m (or equivalent in your environment) to mark that pane.

Marking a pane is useful for certain pane operations; from the section on select-pane:

The marked pane is the default target for -s to join-pane, swap-pane and swap-window.

To clear the mark, press C-b M. If you have M mapped to something else already, you can also use C-b : (to enter the tmux command prompt), followed by select-pane -M to clear the mark.

jjlin
  • 16,120
9

The list of window flags with their explanation can be found in man tmux /STATUS LINE, you’re looking for:

Symbol    Meaning
M         The window contains the marked pane.
dessert
  • 263