mailsync: Check for ZDOTDIR when looking for environmental variables inside .zprofile and .zshrc

[BachoSeven]

Using $HOME/.z{profile,shrc} as a fallback, of course.

~/.profile is not necessarily present when using zsh for login, and setting $ZDOTDIR in ~/.zshenv allows moving .zprofile and .zshrc there.

[BachoSeven]

I've realised this is not working, because ZDOTDIR is not known to mailsync. This issue also applies to #630, in those cases where ~/.profile is not present. For instance, I set both ZDOTDIR and XDG_CONFIG_HOME in ~/.zshenv.

Since this is specific to zsh, we could check if SHELL is zsh, and then run a similar eval "$(grep ...)" command beforehand to export the XDG_CONFIG_HOME and ZDOTDIR variables from ~/.zshenv, since this seems to be the proper way to change the location of zsh files. If you think this is a good solution, I can make another PR.

[BachoSeven]

Okay, SHELL is obviously /bin/sh, but we could use

awk -F: -v user="$USER" '$1 == user {print $NF}' /etc/passwd

which works (source)

[BachoSeven]

This works (just before the eval "$(grep ...)" line):

# Workaround for zsh users who only have .zshenv in their $HOME.
usersh="$(awk -F: -v user="$USER" '$1 == user {print $NF}' /etc/passwd)"
[ "$usersh" = /usr/bin/zsh ] && eval "$(grep -h -- \
	"^\s*\(export \)\?\(ZDOTDIR\|XDG_CONFIG_HOME\|XDG_DATA_HOME\)=" \
	"$HOME/.zshenv" 2>/dev/null)"