diff -ruN a/config.def.h b/config.def.h
--- a/config.def.h	2026-08-25 19:07:53.233903707 +0200
+++ b/config.def.h	2026-08-25 19:07:53.233903707 +0200
@@ -1,5 +1,10 @@
 /* See LICENSE file for copyright and license details. */
 
+/* Defaults below are compile-time. Many can be overridden at runtime by
+ * /etc/ttym.conf and ~/.config/ttym/config; command-line flags override
+ * both. Run `timer --dump-config` for a commented template. See timer(1).
+ */
+
 /* progress bar glyphs (ASCII default) */
 static const char *const BAR_FILL  = ">";
 static const char *const BAR_EMPTY = "-";
diff -ruN a/ttym.c b/ttym.c
--- a/ttym.c	2026-08-25 19:07:53.233903707 +0200
+++ b/ttym.c	2026-08-25 19:07:53.233903707 +0200
@@ -25,13 +25,15 @@
 typedef struct {
 	int quiet;            /* -q: suppress completion bell */
 	int silent;           /* -s: no bell, no extras */
-	const char *title;
-	const char *notify_cmd;
-	const char *sound_cmd;
+	char title[256];      /* runtime config may override */
+	char notify_cmd[512]; /* runtime config may override */
+	char sound_cmd[512];  /* runtime config may override */
 	char msg[1024];
 	int alert_persist;    /* alert loop until keypress; --no-persist disables */
 	int flash;            /* reverse-video flash during alert loop */
 	char bar_style[32];   /* --bar STYLE */
+	char bar_fill[16];    /* runtime config: explicit glyph, beats bar_style */
+	char bar_empty[16];   /* runtime config: explicit glyph, beats bar_style */
 } Config;
 
 static struct termios oldtios;
@@ -352,7 +354,7 @@
 static void
 notify_and_sound(const Config *c)
 {
-	if (c->notify_cmd && c->notify_cmd[0] && command_exists("notify-send")) {
+	if (c->notify_cmd[0] && command_exists("notify-send")) {
 		char **a;
 		if (build_argv(c->notify_cmd, c, &a) > 0) {
 			spawn_bg(a);
@@ -360,7 +362,7 @@
 		}
 	}
 	if (!c->quiet) {
-		if (c->sound_cmd && c->sound_cmd[0]) {
+		if (c->sound_cmd[0]) {
 			char **a;
 			if (build_argv(c->sound_cmd, c, &a) > 0) {
 				spawn_bg(a);
@@ -469,6 +471,178 @@
 	}
 	*fill  = s ? s->fill  : BAR_FILL;
 	*empty = s ? s->empty : BAR_EMPTY;
+	/* explicit glyphs from the config file beat the named style; --bar
+	 * clears them so a flag always wins over the file. */
+	if (c->bar_fill[0])  *fill  = c->bar_fill;
+	if (c->bar_empty[0]) *empty = c->bar_empty;
+}
+
+/* ===== runtime config file =====
+ * key = value lines. '#' starts a comment only at the start of a line or
+ * after whitespace, and never inside quotes. Quote a value to protect
+ * surrounding space or a leading '#'; one matched pair is stripped. Unknown keys and
+ * unparseable values are reported on stderr rather than silently dropped.
+ * Precedence: command-line flags > ~/.config/ttym/config > /etc/ttym.conf
+ * > the compile-time defaults in config.h.
+ */
+
+static int
+build_cfg_path(char *buf, size_t bufsz, const char *name)
+{
+	const char *xdg  = getenv("XDG_CONFIG_HOME");
+	const char *home = getenv("HOME");
+	if (xdg && *xdg)        snprintf(buf, bufsz, "%s/ttym/%s", xdg, name);
+	else if (home && *home) snprintf(buf, bufsz, "%s/.config/ttym/%s", home, name);
+	else                    return -1;
+	return 0;
+}
+
+static void
+trim(char *s)
+{
+	char *p = s;
+	while (*p && isspace((unsigned char)*p)) p++;
+	if (p != s) memmove(s, p, strlen(p) + 1);
+	size_t n = strlen(s);
+	while (n > 0 && isspace((unsigned char)s[n - 1])) s[--n] = '\0';
+}
+
+static void
+strip_comment(char *s)
+{
+	int q = 0;
+	for (char *p = s; *p; p++) {
+		if (q) {
+			if (*p == q) q = 0;
+		} else if (*p == '"' || *p == '\'') {
+			q = *p;
+		} else if (*p == '#' && (p == s || isspace((unsigned char)p[-1]))) {
+			*p = '\0';
+			return;
+		}
+	}
+}
+
+static void
+unquote(char *s)
+{
+	size_t n = strlen(s);
+	if (n >= 2 && (s[0] == '"' || s[0] == '\'') && s[n - 1] == s[0]) {
+		memmove(s, s + 1, n - 2);
+		s[n - 2] = '\0';
+	}
+}
+
+static int
+cfg_bool(const char *path, int ln, const char *k, const char *v, int cur)
+{
+	if (!strcasecmp(v, "true")  || !strcasecmp(v, "yes") ||
+	    !strcasecmp(v, "on")    || !strcmp(v, "1"))  return 1;
+	if (!strcasecmp(v, "false") || !strcasecmp(v, "no") ||
+	    !strcasecmp(v, "off")   || !strcmp(v, "0"))  return 0;
+	fprintf(stderr, "%s:%d: %s: expected on or off, got: %s\n", path, ln, k, v);
+	return cur;
+}
+
+static void
+load_config_file(Config *c, const char *path)
+{
+	FILE *f = fopen(path, "r");
+	if (!f) return;
+	char line[1024];
+	int ln = 0;
+	while (fgets(line, sizeof(line), f)) {
+		ln++;
+		strip_comment(line);
+		char *eq = strchr(line, '=');
+		if (!eq) {
+			trim(line);
+			if (*line)
+				fprintf(stderr, "%s:%d: not key = value: %s\n", path, ln, line);
+			continue;
+		}
+		*eq = '\0';
+		char *k = line, *v = eq + 1;
+		trim(k); trim(v); unquote(v);
+		if (!*k) {
+			fprintf(stderr, "%s:%d: missing key\n", path, ln);
+			continue;
+		}
+		if      (!strcmp(k, "bar_fill"))   snprintf(c->bar_fill,   sizeof(c->bar_fill),   "%s", v);
+		else if (!strcmp(k, "bar_empty"))  snprintf(c->bar_empty,  sizeof(c->bar_empty),  "%s", v);
+		else if (!strcmp(k, "title"))      snprintf(c->title,      sizeof(c->title),      "%s", v);
+		else if (!strcmp(k, "notify_cmd")) snprintf(c->notify_cmd, sizeof(c->notify_cmd), "%s", v);
+		else if (!strcmp(k, "sound_cmd"))  snprintf(c->sound_cmd,  sizeof(c->sound_cmd),  "%s", v);
+		else if (!strcmp(k, "flash"))         c->flash         = cfg_bool(path, ln, k, v, c->flash);
+		else if (!strcmp(k, "alert_persist")) c->alert_persist = cfg_bool(path, ln, k, v, c->alert_persist);
+		else if (!strcmp(k, "bar_style")) {
+			if (find_bar_style(v))
+				snprintf(c->bar_style, sizeof(c->bar_style), "%s", v);
+			else
+				fprintf(stderr, "%s:%d: unknown bar style: %s\n", path, ln, v);
+		}
+		else fprintf(stderr, "%s:%d: unknown key: %s\n", path, ln, k);
+	}
+	fclose(f);
+}
+
+static void
+load_config(Config *c)
+{
+	load_config_file(c, "/etc/ttym.conf");
+	char path[512];
+	if (build_cfg_path(path, sizeof(path), "config") == 0)
+		load_config_file(c, path);
+}
+
+/* Written to stdout by --dump-config; ttym never creates this file itself.
+ *     timer --dump-config > ~/.config/ttym/config
+ */
+static void
+dump_config(FILE *f)
+{
+	fputs(
+"# ttym configuration\n"
+"#\n"
+"# Read from /etc/ttym.conf first, then ~/.config/ttym/config\n"
+"# (honours $XDG_CONFIG_HOME). Command-line flags override both; an absent\n"
+"# or commented-out key keeps the compile-time default from config.h.\n"
+"#\n"
+"# Syntax: key = value. '#' begins a comment at the start of a line or after\n"
+"# whitespace. Quote a value to keep surrounding spaces or a leading '#';\n"
+"# one matched pair of quotes is stripped.\n"
+"# ---------------------------------------------------------------------------\n"
+"\n"
+"# Progress-bar glyphs. Set BOTH or NEITHER -- mismatched display widths\n"
+"# break bar alignment. Multi-byte UTF-8 is fine. These beat bar_style,\n"
+"# but --bar on the command line beats them.\n"
+"# bar_fill  = >          # a '#' glyph must be quoted:  bar_fill = \"#\"\n"
+"# bar_empty = -\n"
+"\n"
+"# Named progress-bar style. One of:\n"
+"#   unicode  ascii  hash  dots  line  block  arrow  minimal\n"
+"# Leave unset to auto-detect (unicode on a UTF-8 locale, otherwise ascii).\n"
+"# bar_style = unicode\n"
+"\n"
+"# Reverse-video flash during the completion alert.   on | off\n"
+"# flash = on\n"
+"\n"
+"# Persistent alert: keep ringing the bell until a key is pressed\n"
+"# (foreground runs only).                            on | off\n"
+"# alert_persist = on\n"
+"\n"
+"# Desktop-notification title.\n"
+"# title = Timer\n"
+"\n"
+"# Desktop-notification command run when a countdown finishes. Tokens are\n"
+"# split on whitespace; {title}/{msg} placeholders expand. Empty disables.\n"
+"# notify_cmd = notify-send -u critical {title} {msg}\n"
+"\n"
+"# Sound played when a countdown finishes. Leave unset to auto-detect a\n"
+"# player (paplay/aplay/mpv/ffplay) and play a default system sound.\n"
+"# Tokens are split on whitespace; {title}/{msg} placeholders expand.\n"
+"# sound_cmd = paplay /usr/share/sounds/freedesktop/stereo/complete.oga\n",
+	f);
 }
 
 /* ===== usage =====
@@ -491,10 +665,12 @@
 "  --no-persist    skip alert-until-keypress loop\n"
 "  --flash on|off  terminal flash during alert loop\n"
 "  --bar STYLE     bar style: unicode|ascii|hash|dots|line|block|arrow|minimal\n"
+"  --dump-config   print a commented config template on stdout and exit\n"
 "  --              end of options\n"
 "  -h              help\n"
 "\n"
-"controls:  [space] pause/resume   [q | Ctrl+C] quit\n");
+"controls:  [space] pause/resume   [q | Ctrl+C] quit\n"
+"config:    /etc/ttym.conf, then ~/.config/ttym/config  (--dump-config)\n");
 }
 
 /* ===== run loop ===== */
@@ -633,12 +809,13 @@
 main(int argc, char **argv)
 {
 	Config cfg = {0};
-	cfg.title      = TITLE;
-	cfg.notify_cmd = NOTIFY_CMD;
-	cfg.sound_cmd  = SOUND_CMD;
+	snprintf(cfg.title,      sizeof(cfg.title),      "%s", TITLE      ? TITLE      : "");
+	snprintf(cfg.notify_cmd, sizeof(cfg.notify_cmd), "%s", NOTIFY_CMD ? NOTIFY_CMD : "");
+	snprintf(cfg.sound_cmd,  sizeof(cfg.sound_cmd),  "%s", SOUND_CMD  ? SOUND_CMD  : "");
 	snprintf(cfg.msg, sizeof(cfg.msg), "%s", "Time is up");
 	cfg.alert_persist = ALERT_PERSIST;
 	cfg.flash         = FLASH;
+	load_config(&cfg);
 
 	/* Pre-strip long-form flags before getopt. Stop at "--". */
 	int nargc = 0, past_dd = 0;
@@ -659,8 +836,13 @@
 		}
 		if (!past_dd && !strcmp(argv[i], "--bar") && i + 1 < argc) {
 			snprintf(cfg.bar_style, sizeof(cfg.bar_style), "%s", argv[++i]);
+			cfg.bar_fill[0] = cfg.bar_empty[0] = '\0';
 			continue;
 		}
+		if (!past_dd && !strcmp(argv[i], "--dump-config")) {
+			dump_config(stdout);
+			return 0;
+		}
 		argv[nargc++] = argv[i];
 	}
 	argv[nargc] = NULL;