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;;; system-commands.el --- System power and session management -*- lexical-binding: t; coding: utf-8; -*-
;; author: Craig Jennings <c@cjennings.net>
;;
;;; Commentary:
;;
;; Layer: 3 (Domain Workflow).
;; Category: D/S.
;; Load shape: eager.
;; Eager reason: registers the C-; ! system-command keymap; high-impact commands
;; that should run only by command (command-loaded target).
;; Top-level side effects: defines a system-command keymap under cj/custom-keymap.
;; Runtime requires: keybindings, rx.
;; Direct test load: yes (requires keybindings explicitly).
;;
;; System commands for logout, lock, suspend, shutdown, reboot, and Emacs
;; exit/restart. Provides both a keymap (C-; !) and a completing-read menu.
;;
;; Commands include:
;; - Logout (terminate user session)
;; - Lock screen (slock)
;; - Suspend (systemctl suspend)
;; - Shutdown (systemctl poweroff)
;; - Reboot (systemctl reboot)
;; - Exit Emacs (kill-emacs)
;; - Restart Emacs (via systemctl --user restart emacs.service)
;;
;; Dangerous commands (logout, suspend, shutdown, reboot) require confirmation.
;;
;;; Code:
;; `keybindings' provides `cj/custom-keymap', which is referenced at load
;; time by the `keymap-set' call at the tail of this file. An
;; `eval-when-compile' require would silence the byte-compiler but leave
;; the load-time reference void if anything required `system-commands'
;; before `keybindings'. Make the dependency explicit.
(require 'keybindings)
(eval-when-compile (require 'subr-x))
(require 'rx)
;; ------------------------------ System Commands ------------------------------
(defun cj/system-cmd--resolve (cmd)
"Return (values symbol-or-nil command-string label) for CMD."
(cond
((symbolp cmd)
(let ((val (and (boundp cmd) (symbol-value cmd))))
(unless (and (stringp val) (not (string-empty-p val)))
(user-error "Variable %s is not a non-empty string" cmd))
(list cmd val (symbol-name cmd))))
((stringp cmd)
(let ((s (string-trim cmd)))
(when (string-empty-p s) (user-error "Command string is empty"))
(list nil s "command")))
(t (user-error "Error: cj/system-cmd expects a string or a symbol"))))
(defun cj/system-cmd (cmd)
"Run CMD (string or symbol naming a string) detached via the shell.
Shell expansions like $(...) are supported. Output is silenced.
If CMD is deemed dangerous, ask for confirmation."
(interactive "sSystem command: ")
;; Plain `let*' + `nth' instead of `pcase-let' with a backquote
;; destructure: edebug-based coverage tools (undercover.el) don't
;; instrument inside backquote-destructured `pcase-let' bindings,
;; so the body shows as uncovered even when tests exercise it.
(let* ((resolved (cj/system-cmd--resolve cmd))
(sym (nth 0 resolved))
(cmdstr (nth 1 resolved))
(label (nth 2 resolved)))
(let ((confirm (and sym (get sym 'cj/system-confirm))))
(cond
;; Strong confirm for irreversible actions (shutdown, reboot):
;; require an explicit "yes", so a stray RET/space can't trigger them.
((eq confirm 'strong)
(unless (yes-or-no-p (format "Really run %s (%s)? " label cmdstr))
(user-error "Aborted")))
;; Quick (Y/n) confirm for recoverable actions (logout, suspend).
(confirm
(when (memq (read-char-choice
(format "Run %s now (%s)? (Y/n) " label cmdstr)
'(?y ?Y ?n ?N ?\r ?\n ?\s))
'(?n ?N))
(user-error "Aborted")))))
(let ((proc (start-process-shell-command "cj/system-cmd" nil
(format "nohup %s >/dev/null 2>&1 &" cmdstr))))
(set-process-query-on-exit-flag proc nil)
(set-process-sentinel proc #'ignore)
(message "Running %s..." label))))
(defmacro cj/defsystem-command (name var cmdstr &optional confirm)
"Define VAR with CMDSTR and interactive command NAME to run it.
CONFIRM controls the confirmation prompt: t for a quick (Y/n) prompt,
the symbol `strong' for an explicit yes-or-no-p (used for irreversible
actions like shutdown and reboot), nil for no confirmation."
(declare (indent defun))
`(progn
(defvar ,var ,cmdstr)
,(when confirm `(put ',var 'cj/system-confirm ',confirm))
(defun ,name ()
,(format "Run %s via `cj/system-cmd'." var)
(interactive)
(cj/system-cmd ',var))))
;; Define system commands
(cj/defsystem-command cj/system-cmd-logout logout-cmd "loginctl terminate-user $(whoami)" t)
(cj/defsystem-command cj/system-cmd-lock lockscreen-cmd "slock")
(cj/defsystem-command cj/system-cmd-suspend suspend-cmd "systemctl suspend" t)
(cj/defsystem-command cj/system-cmd-shutdown shutdown-cmd "systemctl poweroff" strong)
(cj/defsystem-command cj/system-cmd-reboot reboot-cmd "systemctl reboot" strong)
(defun cj/system-cmd-exit-emacs ()
"Exit Emacs server and all clients."
(interactive)
(when (memq (read-char-choice
"Exit Emacs? (Y/n) "
'(?y ?Y ?n ?N ?\r ?\n ?\s))
'(?n ?N))
(user-error "Aborted"))
(kill-emacs))
(defun cj/system-cmd--emacs-service-available-p ()
"Return non-nil if a systemd --user emacs.service unit is present.
Used to decide whether `cj/system-cmd-restart-emacs' can restart via the
service before relying on it to cycle the daemon. `systemctl --user cat'
exits 0 when the unit exists, nonzero otherwise."
(and (executable-find "systemctl")
(eq 0 (call-process "systemctl" nil nil nil
"--user" "cat" "emacs.service"))))
(defun cj/system-cmd-restart-emacs ()
"Restart the Emacs daemon via its systemd --user service, then reconnect.
Aborts without terminating anything when not running as a daemon or when
no emacs.service is present, so a missing or failed service can't leave
you with no Emacs running. The service owns the daemon lifecycle, so
there is no separate `kill-emacs': a failed restart leaves the current
daemon alive rather than killing the session blindly."
(interactive)
(unless (daemonp)
(user-error "Not running as an Emacs daemon; restart Emacs manually"))
(unless (cj/system-cmd--emacs-service-available-p)
(user-error "No systemd --user emacs.service found; restart it manually"))
(when (memq (read-char-choice
"Restart Emacs? (Y/n) "
'(?y ?Y ?n ?N ?\r ?\n ?\s))
'(?n ?N))
(user-error "Aborted"))
(save-some-buffers)
;; Hand the whole restart+reconnect to a detached shell. `systemctl
;; restart' tears down this daemon itself; the detached `emacsclient -c'
;; reconnects to the fresh one.
(call-process-shell-command
(concat "nohup sh -c 'systemctl --user restart emacs.service "
"&& sleep 1 && emacsclient -c' >/dev/null 2>&1 &")
nil 0)
(message "Restarting Emacs via emacs.service..."))
(defun cj/system-command-menu ()
"Present system commands via \='completing-read\='."
(interactive)
(let* ((commands '(("Logout System" . cj/system-cmd-logout)
("Lock Screen" . cj/system-cmd-lock)
("Suspend System" . cj/system-cmd-suspend)
("Shutdown System" . cj/system-cmd-shutdown)
("Reboot System" . cj/system-cmd-reboot)
("Exit Emacs" . cj/system-cmd-exit-emacs)
("Restart Emacs" . cj/system-cmd-restart-emacs)))
(choice (completing-read "System command: " commands nil t)))
(when-let ((cmd (alist-get choice commands nil nil #'equal)))
(call-interactively cmd))))
(defvar-keymap cj/system-command-map
:doc "Keymap for system commands."
"!" #'cj/system-command-menu
"L" #'cj/system-cmd-logout
"r" #'cj/system-cmd-reboot
"s" #'cj/system-cmd-shutdown
"S" #'cj/system-cmd-suspend
"l" #'cj/system-cmd-lock
"E" #'cj/system-cmd-exit-emacs
"e" #'cj/system-cmd-restart-emacs)
(keymap-set cj/custom-keymap "!" cj/system-command-map)
(with-eval-after-load 'which-key
(which-key-add-key-based-replacements
"C-; !" "system commands"
"C-; ! !" "system command menu"
"C-; ! L" "logout"
"C-; ! E" "exit Emacs"
"C-; ! S" "suspend"
"C-; ! e" "restart Emacs"
"C-; ! l" "lock screen"
"C-; ! r" "reboot"
"C-; ! s" "shutdown"))
(provide 'system-commands)
;;; system-commands.el ends here
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