Mix.Release script requires absolute execution path

[xorrvin]

Elixir and Erlang/OTP versions

Elixir 16.2
OTP 26.2.5

Operating system

NetBSD

Current behavior

After producing a release with mix release, resulting main script for a release expects absolute directory path for the invocation.

elixir/lib/mix/lib/mix/tasks/release.init.ex

Lines 90 to 92 in 61acf33

	SELF=$(readlink "$0" || true)
	if [ -z "$SELF" ]; then SELF="$0"; fi
	RELEASE_ROOT="$(CDPATH='' cd "$(dirname "$SELF")/.." && pwd -P)"

It works if you're executing script directly, or if you're making an absolute symlink; in both cases $SELF is an absolute path.
However if one would create a symlink like that:

ln -s ../lib/whatever/bin/test_release bin/test_release

Script execution will fail:

$ test_release
cd: can't cd to ../lib/whatever/bin/..

Usecase:

Trying to make a binary package out of release folder requires either custom prefix (e.g. release folder is copied to /opt/whatever and then PATH is updated) or creating an absolute symlink to /usr/bin or other prefix which is used on a target system.

Relative symlink would allow much easier deployment of Mix.Releases, because it will eliminate post-install step which may not be available for a particular distribution method/system.

Thank you!

Expected behavior

Script works

[josevalim]

A pull request to tackle this is welcome. We may not have time to prioritize this. :)