[shell] respect ZDOTDIR for zsh startup files, and copy startup files instead of linking

[savil]

Summary

Seeks to address two concerns that have arisen:

1. Zsh startup files are linked, not copied. We should copy. This was affecting a user who was mounting the filesystem which disallows linking in that scenario.
   Fixes [Bug]: Fail to link .zshenv and .zprofile - invalid cross-device link #1536

2. ZDOTDIR was not respected for finding the ZSH startup files. We should support it as the zsh manual specifies that its the location of its startup files: https://zsh.sourceforge.io/Intro/intro_3.html
   (Originally for [Bug]: zshenv is not sourced #1582 , but it seems that issue is unrelated to ZDOTDIR)

EDIT: Fixes #1582, as per user who reported the issue

How was it tested?

Tested by setting ZDOTDIR=~/zsh-dot-dir and moving my .zshenv and .zshrc files there. Starting a devbox shell showed that these startup files were run.

Moved them back to my homedir, and unset ZDOTDIR and starting a devbox shell still worked as expected.

[savil]

Current dependencies on/for this PR:

• main
  • PR [shell] respect ZDOTDIR for zsh startup files, and copy startup files instead of linking #1587 👈

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[weilbith]

I currently struggle to figure out if this is already released. Is it? 🙈

EDIT:
Found it. Sorry. Was releases with v0.8.0.
Now my issue: I'm running version v0.8.5, but it still doesn't work for me.

I have the file /etc/zsh/zshenv file with the content export $ZDOTDIR=$XDG_CONFIG_HOME/zsh. Having that, the custom shell configuration (something like /tmp/devbox[0-9]{9}) will not be loaded. And thereby most importantly the PATH variable will not be set. If I comment the ZDOTDIR line, it works fine.

[weilbith]

Where can I see how Zsh is started with the /tmp/devbox* configuration? 🤔
According to the debug output (DEBUG_DEVBOX=1) it runs a Bash explicitly with a --rcfile option argument. For Zsh I only see the binary itself. 🤷🏾

[weilbith]

Just using the devbox shellenv # ... does the job atm. Haven't checked it with all features yet.

EDIT:
Ah, the whole shell configuration features don't work (scripts, init hook, ...)

[savil]

@weilbith it may help to file an issue so we have more info about your system, with the specific files so we can try to reproduce the problem, and can discuss there (rather than in the PR).

I'm unable to repro your problem on my mac.

❯ cat /etc/zshenv
export TEST_FOO1=bar1

export XDG_CONFIG_HOME=/Users/savil/code/jetpack/devbox-projects/weilbith-zsh/xdg-config-home
export ZDOTDIR="${XDG_CONFIG_HOME}/zsh"

❯ cat /Users/savil/code/jetpack/devbox-projects/weilbith-zsh/xdg-config-home/zsh/.zshrc
export TEST_FOO=bar

and then opening a devbox shell works fine with TEST_FOO1 and TEST_FOO being set.

[weilbith]

You are right. Sorry for the noise. Will file in an issue with all details.