bug: non-zero exit codes + messages to stderr produced in non-error context

[DelevoXDG]

Describe the Bug

• Some messages are printed to stderr where streaming them to stdout would be more appropriate.
• Additionally, non-zero exit codes are produced in cases where no failure seem to be present.

Steps to Reproduce

Examples:

1. Updating plugins

   $ asdf plugin update scarb > /dev/null
   updated scarb to ref refs/heads/main

   There seems to be no error, the exit code is 0, yet, the output is sent to stderr, which would indicate that something has gone wrong, even though the contents of the message suggest success.
   Emitted here:

   asdf/internal/cli/cli.go

   Line 1058 in 74d7b17

   logger.Printf("updated %s to ref %s\n", pluginName, updatedToRef)

2. Listing installed versions for plugin that has no versions installed

   $ asdf list scarb > /dev/null
   No compatible versions installed (scarb )
   echo $?                               
   1

   This is unexpected, as normally tools just produce empty list in such context and exit successfully, e.g.

   $ mkdir empty
   $ ls empty > /dev/null
   $ echo $?
   0

   Normally, grep would be used to parse output and exit with error if necessary.

Expected Behaviour

1. Exit code: 0, empty stderr
2. Exit code: 0, empty stderr

Actual Behaviour

1. Exit code: 0, non-empty stderr
2. Exit code: 1, non-empty stderr

Environment

asdf info
OS:
Darwin MacBook-Pro.local 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan  2 20:24:24 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T6030 arm64

SHELL:
zsh 5.9 (arm64-apple-darwin24.0)

BASH VERSION:
5.2.37(1)-release

ASDF VERSION:
0.16.6

ASDF INTERNAL VARIABLES:
ASDF_DEFAULT_TOOL_VERSIONS_FILENAME=.tool-versions
ASDF_DATA_DIR=/Users/delevo/.asdf
ASDF_CONFIG_FILE=/Users/delevo/.asdfrc

asdf plugins affected (if relevant)

No response

[Stratus3D]

Ok to sum up there are two complaints here:

• When asdf list <tool> does not return any versions status code should be 0 instead of 1
• When commands succeed with status of 0 nothing should be printed to STDERR

Both of these are stylistic choices.

For STDERR:

Many commands print to stderr and stdout at the same time under normal operations. The rule that I think we've roughly been following is that STDOUT should contain what the user requested by issuing the command. And STDERR should contain errors or other information not necessarily requested. So in the case of the asdf list <too> command the user is expecting a list of installed versions, not a "No compatible versions installed" message. Printing this to stderr makes scripting much easier - if you want to get a list of installed versions just assign stdout to a variable and split it by line. No special code needs to be written to detect the "No compatible versions installed" message since it's written to a different output.

For status code:

I think your critique is fair, and while status code of 1 might be helpful for in some instances it's not much harder to check if STDOUT is empty and use that to determine that no versions are installed. A PR is welcome for this but it's a breaking change so I can't promise we'll be able to ship it soon.

[Stratus3D]

Changes for status code have been merged and will go out in the next release.