i3: Simulate monitor-independent workspaces

Often when I want to open a new workspace, I look at my bar to see which
workspaces are still free. This does not work sometimes when having
multiple monitors connected, as workspace numbers are unique between all
outputs.

Add a script that handles workspace switching/moving by prepending the
index with the index of the current monitor.

.config/i3/config

@@ -97,29 +97,17 @@ bindsym $mod+space focus mode_toggle
 # focus the parent container
 bindsym $mod+a focus parent
 
-# Set workspace names
-set $ws1 "1"
-set $ws2 "2"
-set $ws3 "3"
-set $ws4 "4"
-set $ws5 "5"
-set $ws6 "6"
-set $ws7 "7"
-set $ws8 "8"
-set $ws9 "9"
-set $ws10 "10"
-
 # switch to workspace
-bindsym $mod+1 workspace $ws1
+bindsym $mod+1 exec ~/.config/i3/multi-monitor-workspaces.sh -s 1
-bindsym $mod+2 workspace $ws2
+bindsym $mod+2 exec ~/.config/i3/multi-monitor-workspaces.sh -s 2
-bindsym $mod+3 workspace $ws3
+bindsym $mod+3 exec ~/.config/i3/multi-monitor-workspaces.sh -s 3
-bindsym $mod+4 workspace $ws4
+bindsym $mod+4 exec ~/.config/i3/multi-monitor-workspaces.sh -s 4
-bindsym $mod+5 workspace $ws5
+bindsym $mod+5 exec ~/.config/i3/multi-monitor-workspaces.sh -s 5
-bindsym $mod+6 workspace $ws6
+bindsym $mod+6 exec ~/.config/i3/multi-monitor-workspaces.sh -s 6
-bindsym $mod+7 workspace $ws7
+bindsym $mod+7 exec ~/.config/i3/multi-monitor-workspaces.sh -s 7
-bindsym $mod+8 workspace $ws8
+bindsym $mod+8 exec ~/.config/i3/multi-monitor-workspaces.sh -s 8
-bindsym $mod+9 workspace $ws9
+bindsym $mod+9 exec ~/.config/i3/multi-monitor-workspaces.sh -s 9
-bindsym $mod+0 workspace $ws10
+bindsym $mod+0 exec ~/.config/i3/multi-monitor-workspaces.sh -s 0
 
 # switch back to the previous workspace
 workspace_auto_back_and_forth yes
@@ -134,28 +122,28 @@ bindsym $mod+Shift+Tab exec i3-msg workspace "$( \
 	head -1)"
 
 # move focused container to workspace
-bindsym $mod+Shift+1 move container to workspace $ws1
+bindsym $mod+Shift+1 exec ~/.config/i3/multi-monitor-workspaces.sh -m 1
-bindsym $mod+Shift+2 move container to workspace $ws2
+bindsym $mod+Shift+2 exec ~/.config/i3/multi-monitor-workspaces.sh -m 2
-bindsym $mod+Shift+3 move container to workspace $ws3
+bindsym $mod+Shift+3 exec ~/.config/i3/multi-monitor-workspaces.sh -m 3
-bindsym $mod+Shift+4 move container to workspace $ws4
+bindsym $mod+Shift+4 exec ~/.config/i3/multi-monitor-workspaces.sh -m 4
-bindsym $mod+Shift+5 move container to workspace $ws5
+bindsym $mod+Shift+5 exec ~/.config/i3/multi-monitor-workspaces.sh -m 5
-bindsym $mod+Shift+6 move container to workspace $ws6
+bindsym $mod+Shift+6 exec ~/.config/i3/multi-monitor-workspaces.sh -m 6
-bindsym $mod+Shift+7 move container to workspace $ws7
+bindsym $mod+Shift+7 exec ~/.config/i3/multi-monitor-workspaces.sh -m 7
-bindsym $mod+Shift+8 move container to workspace $ws8
+bindsym $mod+Shift+8 exec ~/.config/i3/multi-monitor-workspaces.sh -m 8
-bindsym $mod+Shift+9 move container to workspace $ws9
+bindsym $mod+Shift+9 exec ~/.config/i3/multi-monitor-workspaces.sh -m 9
-bindsym $mod+Shift+0 move container to workspace $ws10
+bindsym $mod+Shift+0 exec ~/.config/i3/multi-monitor-workspaces.sh -m 0
 
 # move focused container and switch to workspace
-bindsym Mod1+Shift+1 move container to workspace $ws1; workspace $ws1
+bindsym Mod1+Shift+1 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 1
-bindsym Mod1+Shift+2 move container to workspace $ws2; workspace $ws2
+bindsym Mod1+Shift+2 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 2
-bindsym Mod1+Shift+3 move container to workspace $ws3; workspace $ws3
+bindsym Mod1+Shift+3 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 3
-bindsym Mod1+Shift+4 move container to workspace $ws4; workspace $ws4
+bindsym Mod1+Shift+4 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 4
-bindsym Mod1+Shift+5 move container to workspace $ws5; workspace $ws5
+bindsym Mod1+Shift+5 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 5
-bindsym Mod1+Shift+6 move container to workspace $ws6; workspace $ws6
+bindsym Mod1+Shift+6 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 6
-bindsym Mod1+Shift+7 move container to workspace $ws7; workspace $ws7
+bindsym Mod1+Shift+7 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 7
-bindsym Mod1+Shift+8 move container to workspace $ws8; workspace $ws8
+bindsym Mod1+Shift+8 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 8
-bindsym Mod1+Shift+9 move container to workspace $ws9; workspace $ws9
+bindsym Mod1+Shift+9 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 9
-bindsym Mod1+Shift+0 move container to workspace $ws10; workspace $ws10
+bindsym Mod1+Shift+0 exec ~/.config/i3/multi-monitor-workspaces.sh -ms 0
 
 # reload the configuration file
 bindsym $mod+Shift+c reload

.config/i3/multi-monitor-workspaces.sh

@@ -0,0 +1,54 @@
+#!/bin/sh
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2025 Julian Prein
+#
+# Script to simulate output-independent workspaces. Can be used to switch and/or
+# move a container to the workspace.
+
+set -eu
+
+switch=
+move=
+
+usage() {
+	printf >&2 "Usage: %s [-s] [-m] <index>\n" "$0"
+	exit "${1:-0}"
+}
+
+while getopts "sm" flag; do
+	case $flag in
+		s) switch=1;;
+		m) move=1;;
+		*) usage 1;;
+	esac
+done
+shift $((OPTIND - 1))
+[ $# -gt 0 ] || usage
+
+outputs="$(i3-msg -t get_outputs | jq -r '.[] | select(.active).name')"
+num_outs="$(printf "%s\n" "$outputs" | wc -l)"
+
+if [ "$num_outs" -lt 2 ]; then
+	# only one monitor
+	workspace="$1"
+else
+	name="$(i3-msg -t get_tree \
+		| jq -r '.. | objects | select(.focused).output')"
+	num="$(printf "%s\n" "$outputs" \
+		| grep -Fxn "$name" \
+		| cut -d: -f1)"
+	num="$((num - 1))"
+
+	# Omit the number on the first monitor
+	[ "$num" -gt 0 ] || num=
+
+	workspace="$num$1"
+fi
+
+if [ -z "$switch" ] && [ -z "$move" ]; then
+	printf "%s\n" "$workspace"
+	exit 0
+fi
+
+[ -z "$move" ] || i3-msg move container to workspace "$workspace"
+[ -z "$switch" ] || i3-msg workspace "$workspace"