Terminal window resizement not passed through via "su -c"

[blueyed]

I have noticed that with the following invocation, terminal window resizements (e.g. maximize / restore) do not appear to get through to tmux:

mosh --ssh='ssh -AX -tt' example.com -- su -plc 'tmux new-session -s main -A'

It works when using ssh directly:

ssh -AX -t example.com -- "su -plc 'tmux new-session -s main -A'"

It also works when calling su - only, where tmux then gets invoked from the zshrc file:

mosh --ssh='ssh -AX -tt' example.com -- su -

The same is true for just "su -c" instead of "su -plc".

[andersk]

I cannot reproduce your second claim (“It works when using ssh directly”). For me it does not even work locally (su -c tmux or su -plc tmux). According to su(1),

-c, --command COMMAND

Specify a command that will be invoked by the shell using its -c.

The executed command will have no controlling terminal. This option cannot be used to execute interractive programs which need a controlling TTY.

Without a TTY, tmux can’t receive SIGWINCH terminal resize events. Consider using a different utility to gain root, such as sudo.

[andersk]

(By the way, --ssh='ssh -AX -tt' doesn’t accomplish anything. Mosh closes the ssh connection immediately upon mosh-server startup; neither SSH agent forwarding nor X forwarding are supported. And mosh always passes -tt.)