Am I missing something obvious? When did this get so hard?
In the old days, you configured your desktop session on a Linux system by editing the .xsession file in your home directory. The display manager (login screen) would invoke the system-wide xsession script, which would either defer to your personal .xsession script or set up a standard desktop environment. You could put whatever you want in the .xsession script, and it would be executed. If you wanted a specific window manager, you d run it from .xsession. Start emacs or a browser or an xterm or two? .xsession. It was pretty easy, and super flexible.
For the past 25 years or so, I ve used X with an environment started via .xsession. Early on it was fvwm with some programs, then I replaced fvwm with
Window Maker (before that was even its name!), then switched to
KDE. More recently (OK, like 10 years ago) I gradually replaced KDE with
awesome and various custom widgets. Pretty much everything was based on a .xsession script, and that was fine. One particularly nice thing about it was that I could keep .xsession and any related helper programs in a git repository and manage changes over time.
More recently I decided to give Wayland and GNOME an honest look. This has mostly been fine, but everything I ve been doing in .xsession is suddenly useless.
OK, fine, progress is good. I ll just use whatever new mechanisms exist. How hard can it be?
OK, so here we go. I am running GNOME. This isn t so bad. Alt+F2 brings up the Run Command dialog. It s a different keystroke than what I m used to, but I can adapt. (Obviously I can reconfigure the key binding, and maybe someday I will, but that s not the point here.) I have some executables in ~/bin. Oops, the run command dialog can t find them. No problem, I just need to update the PATH variable that it sees. Hmmm So how does one do that, anyway? GNOME has a help system, but searching that doesn t doesn t reveal anything. But that s fine, maybe it s inherited from the parent process. But there s no xsession script equivalent, since this isn t X anymore at all. The familiar stuff in /etc/X11/Xsession is no longer used. What s the equivalent in Wayland? Turns out, there isn t a shell script at all anymore, at least not in how Wayland and GNOME interact in Debian s configuration, which seems fairly similar to how anybody else would set this up. The GNOME session runs from a systemd-managed user session.
Digging in to some web search results suggests that systemd provides
a mechanism for setting some environment variables for services started by the user instance of the system. OK, so let s create some files in ~/.config/environment.d and we should be good. Except no, this isn t working. I can set some variables, but something is overriding PATH. I can create this file:
$ cat ~/.config/environment.d/01_path.conf
USER_INITIAL_PATH=$ PATH
PATH=$ HOME /bin:$ HOME /go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
USER_CUSTOM_PATH=$ PATH
After logging in, the Run a command dialog still doesn t see my PATH. So I use Alt+F2 and
sh -c "env > /tmp/env" to capture the environment, and this is what I see:
USER_INITIAL_PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PATH=/usr/local/bin:/usr/bin:/bin:/usr/games
USER_CUSTOM_PATH=/home/noahm/bin:/home/noahm/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
So, my environment.d file is there, and it s getting looked at, but something else is clobbering my PATH later in the startup process. But what? Where? Why? The systemd docs don t indicate that there s anything special about PATH, and nothing in /lib/systemd/user-environment-generators/ seems to treat it specially. The string PATH doesn t appear in /lib/systemd/user/ either. Looking for the specific value that s getting assigned to PATH in /etc shows the only occurrence of it being in /etc/zsh/zshenv, so maybe that s where it s coming from? But that should only get set there if it s otherwise unset or otherwise very minimally set. So I still have no idea where it s coming from.
OK, so ignoring where my custom value is getting overridden, maybe what s configured in /lib/systemd/user will point me in the right direction.
systemd --user status suggests that the interesting part of my session is coming from gnome-shell-wayland.service. Can we use a standard systemd drop-in as documented in
systemd.unit(5)? It turns out that we can. This file sets things up the way I want:
$ cat .config/systemd/user/gnome-shell-wayland.service.d/path.conf
[Service]
Environment=PATH=%h/bin:%h/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
Is that right? It really doesn t feel ideal to me. Systemd s Environment directive can t reference existing environment variables, and I can t use conditionals to do things like add a directory to the PATH only if it exists, so it s still a functional regression from what we had before. But at least it s a text file, edited by hand, trackable in git, so that s not too bad.
There are some people out there who hate systemd, and will cite this as an illustration of why. However, I m not one of those people, and I very much like systemd as an init system. I d be happy to throw away sysvinit scripts forever, but I m not quite so happy with the state of .xsession s replacements. Despite the similarities, I don t think .xsession is entirely the same as SysV-style init scripts. The services running on a system are vastly more important than my personal .xsession, and systemd is far better at managing them than the pile of shell scripts used to set things up under sysvinit. Further, systemd the init system maintains compatibility with init scripts, so if you really want to keep using them, you can. As far as I can tell, though, systemd the user session manager does not seem to maintain compatibility with .xsession scripts, and that s unfortunate.
I still haven t figured out what was overriding the ~/.config/environment.d/ setting. Any ideas?