I have this in my i3 config to restart picom:
bindsym $mod+Shift+P exec killall picom; sleep 0.2; picom
It works fine in terminal but when I press the keybinding, it shows error, and it just says you have error in this line but don't tell which error.
See https://i3wm.org/docs/userguide.html#exec and, semicolons have special meaning in i3:
See [command_chaining] for details on the special meaning of ; (semicolon) and , (comma): they chain commands together in i3, so you need to use quoted strings (as shown in [exec_quoting]) if they appear in your command.
and
Commands can be chained by using ; (a semicolon)
so bindsym $mod+Shift+P exec killall picom; sleep 0.2; picom tries to bind $mod-shift-P to exec killall picom, followed by the i3 command sleep 0.2, followed by the i3 command picom. The latter two are not i3 commands.
I suggest moving killall picom; sleep 0.2; picom into a shell script and instead bind $mod-shift-P to that shell script with bindsym $mod+Shift+P exec /path/to/script.sh.
