im-launch in Ubuntu startup

-e check the file /usr/bin/ibus-daemon exists or not? exist means true does not exist means false.

! wants to confirm above value is false if above value is true, it will not execute anything.

[ "x$XDG_SESSION_TYPE" = "xwayland" ] this can have either one of below values based on how you choose to login at the login screen. which session you will choose x11 or wayland.

"xx11" = "xwayland" "xwayland" = "xwayland"

example output of $XDG_SESSION_TYPE

administrator@pratap:~$ echo $XDG_SESSION_TYPE
x11

another example:

administrator@pratap:~$ echo $XDG_SESSION_TYPE
wayland
administrator@pratap:~$ 

if the first expression is false and x$XDG_SESSION_TYPE = xwayland then exec the command env IM_CONFIG_CHECK_ENV=1 im-launch true

if the first expression is true or x$XDG_SESSION_TYPE is not equal to xwayland then don't do anything.

see man test

! EXPRESSION
              EXPRESSION is false

and

   -e FILE
          FILE exists

you can read more about what this command does then exec env IM_CONFIG_CHECK_ENV=1 im-launch true;

see man env & man im-launch

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By default in Ubuntu 19.10 /usr/bin/ibus-daemon exists. so the command will not be executed.

env IM_CONFIG_CHECK_ENV=1 im-launch true

when there is the file /usr/bin/ibus-daemon and my session is x11

here is something about IM

when there is no file /usr/bin/ibus-daemon and my session is wayland

here is the thing which is different from above, which means the env is applied and then a chain reaction followed.

so, if you disable or enable this from startup list nothing happens unless no existence of this file /usr/bin/ibus-daemon and your session is wayland conditions are met.