/cc current maintainers of the xonsh package: @spwhitt, @vrthra

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/can-i-use-xonsh-as-my-login-shell-if-so-how/6472/8

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review-may-2019/3032/142

There is only one issue I noticed: the warning about aliases (only ls for me) beign ignored because they would override a xonsh built-in alias. I'm not sure which option between ignoring with --suppress-skip-message or overwriting with --overwrite-alias is better but the warning is pretty annoying if you are using this as your daily shell.

>>> aliases
xonsh.aliases.Aliases(
{'EOF': <function xonsh.aliases.xonsh_exit>,
 'bg': <function xonsh.jobs.bg>,
 'cd': <function xonsh.dirstack.cd>,
 'completer': <function xonsh.completers._aliases.completer_alias>,
 'dirs': <function xonsh.dirstack.dirs>,
 'egrep': ['egrep', '--color=auto'],
 'exec': <function xonsh.aliases.xexec>,
 'exit': <function xonsh.aliases.xonsh_exit>,
 'fg': <function xonsh.jobs.fg>,
 'fgrep': ['fgrep', '--color=auto'],
 'grep': ['grep', '--color=auto'],
 'history': <function xonsh.history.main.history_main>,
 'ipynb': ['jupyter', 'notebook', '--no-browser'],
 'jobs': <function xonsh.jobs.jobs>,
 'popd': <function xonsh.dirstack.popd>,
 'pushd': <function xonsh.dirstack.pushd>,
 'quit': <function xonsh.aliases.xonsh_exit>,
 'replay': <function xonsh.replay.replay_main>,
 'scp-resume': ['rsync', '--partial', '-h', '--progress', '--rsh=ssh'],
 'showcmd': <function xonsh.aliases.showcmd>,
 'source': <function xonsh.aliases.source_alias>,
 'source-bash': ['source-foreign', 'bash', '--sourcer=source'],
 'source-cmd': <function xonsh.aliases.source_cmd>,
 'source-foreign': <function xonsh.aliases.source_foreign>,
 'source-zsh': ['source-foreign', 'zsh', '--sourcer=source'],
 'timeit': <function xonsh.timings.timeit_alias>,
 'trace': <function xonsh.aliases.trace>,
 'which': <function xonsh.xoreutils.which.which>,
 'xexec': <function xonsh.aliases.xexec>,
 'xonfig': <function xonsh.aliases.xonfig>,
 'xonsh-reset': <function xonsh.aliases.xonsh_reset>,
 'xontrib': <function xonsh.xontribs.xontribs_main>,
 'xpip': ['sudo',
  '/nix/store/ljbn79cwlwvrlmqil0nk4zvf043ph592-python3-3.7.5/bin/python3.7',
  '-m',
  'pip']})

Therefore, I'm reluctant to --overwrite-alias which potentially would let the NixOS environment silently override important xonsh commands.

On the other hand, --suppress-skip-message could silently discard aliases the user specified in NixOS option environment.shellAliases.

Thus I think we should gracefully handle the known alias collision(s), but have that warning message appear again for unexpected collisions. For an otherwise default configuration, ls seems indeed to be the only colliding alias name.

Xonsh sets ls to ls --color=auto -v while Bash picks up the ls alias ls --color=tty from a environment.shellAliases default override value. Those are similar enough that it shouldn't much matter, which one we choose. I arbitrarily decided to keep xonsh's and have implemented that in this change to this PR.

If you have no objections I'm going to merge this: it's already an improvement over the current state of xonsh.

If you have no objections I'm going to merge this:

Me? Despite my warning in the PR description, I have no objections to merging this, or I would have filed it as WIP PR instead of regular PR.

The warning is just there to manage expectations. 😉

it's already an improvement over the current state of xonsh.

That's my take, too, @rnhmjoj. Let's ship it!

Should it be backported to 20.03 or would that be too surprising a change?

That's my take, too, @rnhmjoj. Let's ship it!

Good, let's do it.

Should it be backported to 20.03 or would that be too surprising a change?

Uhm, I'm not too keen on backporting non-bugfix changes after the feature-freeze. It should probably be safe but it may have some unintended consequences...

⚠️ Note that even with that change, setting users.users.<name?>.shell to xonsh for my user prevents me from successfully logging into GNOME 3 from GDM (and maybe prevents any graphical login - didn't test with other login managers or DEs / WMs, yet). But at least I get a usable xonsh shell in text mode (virtual terminal accessible with Ctrl-Alt-F1 etc.), which I didn't get without this change. (Without the change, xonsh would start on login, but would be nearly unusable as almost all external commands would have to be invoked through their absolute path, because they wouldn't be on $PATH.)

Tried it on nixos-unstable now and it works fine with GNOME 3. 🎉

Dunno what was up when I tried it on release-19.09

@das-g I was down the same adventure as you yesterday. I've successfully managed to make xonsh my login shell in TTY, but SDDM->KDE fails.

I also had to configure wrap xonsh in a shell script to set XDG_CONFIG_HOME set before launching it, else it'd fail finding RC files.

Are you still running xonsh as your login shell?

Are you still running xonsh as your login shell?

Yes, I am, @Lillecarl. But quite some stuff doesn't work as I'd expect in my setup, e.g. there's no command completion for Git subcommands and their arguments and options. PRs welcome!

@das-g https://github.com/Lillecarl/nixos/blob/master/lillecarl/dotfiles/.config/xonsh/rc.xsh#L41 Not sure if that's related to your issue, but for me adding bash completion support from current-system worked out just great, I have bash-completions for git, and a lot of other tools.