zsh: Partial incompatibility with romkatv/powerlevel10k instant prompt

[volfyd]

Powerlevel10k instant prompt is a neat feature where a quite complex prompt can be initially displayed without fully loading .zshrc. During the loading of .zshrc, standard in is redirected to /dev/null.

https://github.com/romkatv/powerlevel10k/blob/master/README.md

When instant prompt is enabled, for the duration of Zsh initialization standard input is redirected to /dev/null and standard output with standard error are redirected to a temporary file. Once Zsh is fully initialized, standard file descriptors are restored and the content of the temporary file is printed out.

This causes problems with mcfly.

The command eval "$(mcfly init zsh)" runs the following as the first command:

# Ensure stdin is a tty
[[ -t 0 ]] || return

This causes the eval to return an error I think. I saw very odd behavior where the zsh prompt would load every other xterm I opened. The other half of the time, the powerlevel10k (p10k) wizard would open.

I was able to solve this by changing the command in .zshrc to

eval "$(mcfly init zsh)" < /dev/tty

I would say that the Powerlevel10k behavior is strange, but it is an exceptionally popular plugin so it may make sense to either document this problem or to code around it.

[cantino]

Does if [ -t 1 ]; then return 0; fi from https://github.com/cantino/mcfly/issues/154#issuecomment-856262557 fix it?

[volfyd]

@cantino That line is almost the opposite logic of the original logic. The original logic returns if FD 0 is NOT a TTY. The logic in

if [ -t 1 ]; then return 0; fi

is the opposite where it returns if FD 1 IS a TTY. I think it will break folks who do not have an unusual setup where the FD are being redirected.

[cantino]

Thank you @volfyd. I guess we want if [[ ! -t 0 ]]; then return 0; fi then?

[stepanselyuk]

[[ ! -o interactive ]] && return 0

this works for me

[cantino]

Can you see if https://github.com/cantino/mcfly/pull/164 fixes this?