Index: ifconfig.c
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.c,v
retrieving revision 1.440
diff -u -p -r1.440 ifconfig.c
--- ifconfig.c	13 Mar 2021 21:23:29 -0000	1.440
+++ ifconfig.c	15 Mar 2021 01:33:23 -0000
@@ -255,6 +255,7 @@ void	unsettrunkport(const char *, int);
 void	settrunkproto(const char *, int);
 void	settrunklacpmode(const char *, int);
 void	settrunklacptimeout(const char *, int);
+void	linkwait(const char *, int);
 void	trunk_status(void);
 void	list_cloners(void);
 
@@ -669,6 +671,7 @@ const struct	cmd {
 	{ "inst",	NEXTARG,	A_MEDIAINST,	setmediainst },
 	{ "lladdr",	NEXTARG,	0,		setiflladdr },
 	{ "llprio",	NEXTARG,	0,		setifllprio },
+	{ "wait",	NEXTARG,	0,		linkwait },
 	{ NULL, /*src*/	0,		0,		setifaddr },
 	{ NULL, /*dst*/	0,		0,		setifdstaddr },
 	{ NULL, /*illegal*/0,		0,		NULL },
@@ -6710,6 +6713,35 @@ setiflladdr(const char *addr, int param)
 	bcopy(eap, ifr.ifr_addr.sa_data, ETHER_ADDR_LEN);
 	if (ioctl(sock, SIOCSIFLLADDR, (caddr_t)&ifr) == -1)
 		warn("SIOCSIFLLADDR");
+}
+
+void
+linkwait(const char *arg, int param)
+{
+	int waittime;
+	const char *errstr;
+	struct if_data ifrdat;
+
+	waittime = strtonum(arg, 1, 120, &errstr);
+	if (errstr != NULL)
+		errx(1, "%s wait time %s: %s", ifname, arg, errstr);
+
+	do {
+		memset(&ifr, 0, sizeof(ifr));
+		memset(&ifrdat, 0, sizeof(ifrdat));
+
+		strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+		ifr.ifr_data = (caddr_t)&ifrdat;
+		if (ioctl(sock, SIOCGIFDATA, (caddr_t)&ifr) == -1)
+			err(1, "%s SIOCGIFDATA", ifname);
+
+		if (LINK_STATE_IS_UP(ifrdat.ifi_link_state))
+			return;
+
+		sleep(1);
+	} while (--waittime > 1);
+
+	errx(1, "%s wait %s expired", ifname, arg);
 }
 
 #ifndef SMALL