From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Maximilian Bosch Date: Fri, 1 Sep 2023 09:57:02 +0200 Subject: [PATCH] systemctl-edit: suggest `systemdctl edit --runtime` on system scope This is a NixOS-specific change. When trying to modify a unit with `systemctl edit` on NixOS, it'll fail with "Read-only file system": $ systemctl edit libvirtd Failed to open "/etc/systemd/system/libvirtd.service.d/.#override.conffa9825a0c9a249eb": Read-only file system This is because `/etc/systemd/system` is a symlink into the store. In fact, I'd consider this a feature rather than a bug since this ensures I don't introduce state imperatively. However, people wrongly assume that it's not possible to edit units ad-hoc and re-deploy their system for quick&dirty debugging where this would be absolutely fine (and doable with `--runtime` which adds a transient and non-persistent unit override in `/run`). To make sure that people learn about it quicker, this patch throws an error which suggests using `--runtime` when running `systemctl edit` on the system scope. For the user scope this isn't needed because user-level unit overrides are written into `$XDG_CONFIG_HOME/systemd/user`. --- src/systemctl/systemctl-edit.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/systemctl/systemctl-edit.c b/src/systemctl/systemctl-edit.c index e3f25d52d5..81c9c6f6b7 100644 --- a/src/systemctl/systemctl-edit.c +++ b/src/systemctl/systemctl-edit.c @@ -323,6 +323,9 @@ int verb_edit(int argc, char *argv[], void *userdata) { sd_bus *bus; int r; + if (!arg_runtime && arg_runtime_scope == RUNTIME_SCOPE_SYSTEM) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "The unit-directory '/etc/systemd/system' is read-only on NixOS, so it's not possible to edit system-units directly. Use 'systemctl edit --runtime' instead."); + if (!on_tty()) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Cannot edit units if not on a tty.");