Systemd & Shell Integration Reference

The units installed and enabled by postinstall.sh, plus the pos bash completion.

Services
Per-user units (pos network download)
Stop behavior
Feature-flag gating
Bash completion

Services

postinstall.sh copies every systemd/*.service (and systemd/*.timer) to /etc/systemd/system/, runs systemctl daemon-reload, then enables each one (see the gating rule below).

autostart.service

Purpose: run features/autostart.sh at boot (after the network is online) and keep retrying if it fails.

[Unit]
Description=My Linux Autostart Script
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart=/usr/local/bin/autostart.sh
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

Configuration: point ExecStart at your boot script. Because the target script is a feature, this unit is only enabled when the autostart flag is set — the file is still copied, but a skipped feature leaves the unit present-but-disabled.

usb-automount.service

Purpose: mount USB storage automatically — at boot (via WantedBy=multi-user.target) and on hotplug (a udev rule installed by the feature script triggers this unit). Each run mounts every unmounted removable block device at /media/<label>, world-writable (-o umask=000), so pos system backup's post-verify USB copy finds the stick and the unprivileged user can write to it.

[Unit]
Description=Auto-mount USB storage (usb-automount feature)
After=local-fs.target

[Service]
Type=oneshot
ExecStart=/usr/local/bin/usb-automount.sh

[Install]
WantedBy=multi-user.target

Configuration: Type=oneshot — each start (boot, hotplug, manual systemctl start usb-automount) does one idempotent scan. features/usb-automount.sh self-installs its udev rule (/etc/udev/rules.d/99-usb-automount.rules, SYSTEMD_WANTS="usb-automount.service") on first root run and reloads udev, so plugging in a stick fires the mount with no extra setup; an edited rule is never overwritten. Because the target script is a feature, this unit is only enabled when the usb-automount flag is set — the file is still copied, but a skipped feature leaves the unit present-but-disabled. Hotplug is restricted to USB (ENV{ID_BUS}=="usb"); the boot scan covers all removable media.

ssh-agent.service

Purpose: a system-wide SSH agent, one shared socket for all sessions (so pos ssh load-keys and everyday ssh work without per-login agents).

[Unit]
Description=SSH Authentication Agent
After=network.target

[Service]
Type=simple
ExecStartPre=mkdir -p /run/ssh-agent
ExecStart=/usr/bin/ssh-agent -D -a /run/ssh-agent/socket
ExecStartPost=/bin/sh -c 'chmod 666 /run/ssh-agent/socket'
ExecStopPost=/bin/sh -c 'rm -f /run/ssh-agent/socket'
Restart=on-failure

[Install]
WantedBy=multi-user.target

Configuration: socket at /run/ssh-agent/socket (world-readable/writable). ~/.bashrc (set by postinstall.sh) exports SSH_AUTH_SOCK to it. Gated on the ssh-agent feature flag — only enabled when the flag is set (./install.sh --feature or flag-set ssh-agent).

Per-user units (`pos network download`)

The aria2 download tool installs user-scope units (not by postinstall): written to ~/.config/systemd/user/ and enabled with systemctl --user on first use, so they need no sudo.

pos-aria2.service — the daemon (Type=simple, Restart=on-failure, WantedBy=default.target): runs aria2c --enable-rpc --rpc-listen-port=6800 --rpc-secret=… --dir=$HOME/Downloads --continue=true --max-connection-per-server=16 --split=16 --seed-time=0. pos network download start generates the RPC_SECRET into ~/.config/linux_post_install/download.env (chmod 600).
pos-aria2-retry.service — Type=oneshot; ExecStart=<pos> network download retry all --once --quiet (runner = /usr/local/bin/pos-network-download, repo-path fallback with a warning). Driven only by its companion timer.
pos-aria2-retry.timer — OnUnitActiveSec=2min + OnBootSec=2min, AccuracySec=30s, Persistent=true, WantedBy=timers.target. Arms itself when a download starts (add/torrent/metalink/restart) and disables itself when no active, waiting, or errored downloads remain.

On headless boxes pos network download start prints a loginctl enable-linger warning so the user units survive logout.

Stop behavior

Every pos unit — the tool-written user units (pos-aria2, pos-aria2-retry, scheduler-lib.sh job units, entertainment-lib.sh plugin units, the Telegram and Matrix listener units) and the shipped systemd/*.service files — sets TimeoutStopSec=5s so nothing can stall a reboot for the systemd default of 90s. The two long-polling listener daemons also trap TERM INT in their poll loop (kills in-flight curl, exits 0), so systemctl --user stop returns in well under a second; TimeoutStopSec is the backstop if a process ignores SIGTERM. A oneshot job that happens to be running at shutdown gets SIGKILLed 5s after stop begins — timers are Persistent, so the work re-runs next boot.

Feature-flag gating

The systemd loop in postinstall.sh special-cases three units:

if [ "$svc_name" = "autostart.service" ] && ! flag_is_set autostart; then
    warn "autostart feature not installed — skipping autostart.service (run ./install.sh --feature)"
    continue
fi
if [ "$svc_name" = "usb-automount.service" ] && ! flag_is_set usb-automount; then
    warn "usb-automount feature not installed — skipping usb-automount.service (run ./install.sh --feature)"
    continue
fi
if [ "$svc_name" = "ssh-agent.service" ] && ! flag_is_set ssh-agent; then
    warn "ssh-agent feature not installed — skipping ssh-agent.service (run ./install.sh --feature)"
    continue
fi

autostart.service is enabled only when the autostart feature flag is set (./install.sh --feature or flag-set autostart). See SCRIPTS.md → lib/flags.sh.
usb-automount.service is enabled only when the usb-automount feature flag is set — same mechanism.
ssh-agent.service is enabled only when the ssh-agent feature flag is set — same mechanism.

Bash completion

File: completions/pos.bash Purpose: tab-completion for the pos CLI.

How it works

Dynamically discovers subcommands by listing executable pos-* files next to the pos binary — no hard-coded command list, so new tools complete automatically.
Works with the bash-completion package (_init_completion) and falls back to a manual init if it isn't loaded.
Provides completion for the first two words of pos <category> <command>.

Configuration

Installed by postinstall.sh to /usr/local/share/bash-completion/completions/pos.bash and sourced from ~/.bashrc. To load it manually: source completions/pos.bash (or copy into /etc/bash_completion.d/).

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