--- src/usr.bin/nc/nc.1

+++ src/usr.bin/nc/nc.1

@@ -35,6 +35,7 @@

 .Nm nc

 .Bk -words

 .Op Fl 46DdhklnrStUuvz

+.Op Fl e Ar command

 .Op Fl I Ar length

 .Op Fl i Ar interval

 .Op Fl O Ar length

@@ -100,6 +101,9 @@ to use IPv6 addresses only.

 Enable debugging on the socket.

 .It Fl d

 Do not attempt to read from stdin.

+.It Fl e Ar command

+Starts specified command for communicating with remote side

+after connection is established.

 .It Fl h

 Prints out

 .Nm

@@ -415,6 +419,11 @@ The same example again, this time enabling proxy authentication with username

 if the proxy requires it:

 .Pp

 .Dl $ nc -x10.2.3.4:8080 -Xconnect -Pruser host.example.com 42

+.Pp

+Listen on port 1234, send system name to connected client and exit:

+.Pp

+.Dl $ nc -l -v -e 'cat /etc/altlinux-release; uname -a' 1234

+.Pp

 .Sh SEE ALSO

 .Xr cat 1 ,

 .Xr ssh 1

--- src/usr.bin/nc/netcat.c

+++ src/usr.bin/nc/netcat.c

@@ -104,6 +104,7 @@ int	Tflag = -1;				/* IP Type of Service */

 #ifdef HAVE_SO_RTABLE

 u_int	rtableid;

 #endif

+char   *opt_exec = NULL;			/* Program to execute after connecting */

 int timeout = -1;

 int family = AF_INET;

@@ -111,6 +112,7 @@ char *portlist[PORT_MAX+1];

 void	atelnet(int, unsigned char *, unsigned int);

 void	build_ports(char *);

+void	execcmd(int fd);

 void	help(void);

 int	local_listen(char *, char *, struct addrinfo);

 void	readwrite(int);

@@ -168,7 +170,7 @@ main(int argc, char *argv[])

 		usage(1);

 	while ((ch = getopt(argc, argv,

-	    "46DdhI:i:jklnO:P:p:rSs:tT:UuV:vw:X:x:z")) != -1) {

+	    "46Dde:hI:i:jklnO:P:p:rSs:tT:UuV:vw:X:x:z")) != -1) {

 		switch (ch) {

 		case '4':

 			family = AF_INET;

@@ -192,6 +194,11 @@ main(int argc, char *argv[])

 		case 'd':

 			dflag = 1;

 			break;

+		case 'e':   /* prog to exec */

+			if (opt_exec)

+				errx(1, "cannot specify `-e' option double");

+			opt_exec = strdup(optarg);

+			break;

 		case 'h':

 			help();

 			break;

@@ -317,6 +324,8 @@ main(int argc, char *argv[])

 		errx(1, "cannot use -p and -l");

 	if (lflag && zflag)

 		errx(1, "cannot use -z and -l");

+	if (zflag && opt_exec)

+		errx(1, "cannot use -z and -e");

 	if (!lflag && kflag)

 		errx(1, "must use -l with -k");

@@ -490,6 +499,43 @@ main(int argc, char *argv[])

 }

 /*

+ *  execcmd()

+ *  Execute an external file making its stdin/stdout/stderr

+ *  the actual socket. Returns never.

+ */

+void

+execcmd(int fd)

+{

+	int saved_stderr;

+	char *p;

+

+	/* save the stderr fd because we may need it later */

+	saved_stderr = dup(STDERR_FILENO);

+

+	/* duplicate the socket for the child program */

+	dup2(fd, STDIN_FILENO);               /* the precise order of fiddlage */

+	close(fd);                            /* is apparently crucial; this is */

+	dup2(STDIN_FILENO, STDOUT_FILENO);    /* swiped directly out of "inetd". */

+	dup2(STDIN_FILENO, STDERR_FILENO);    /* also duplicate the stderr channel */

+

+	/* change the label for the executed program */

+	if ((p = strrchr(opt_exec, '/'))) {

+		p++;                          /* shorter argv[0] */

+	} else {

+		p = opt_exec;

+	}

+

+	/* replace this process with the new one */

+#ifndef USE_OLD_COMPAT

+	execl("/bin/sh", p, "-c", opt_exec, NULL);

+#else

+	execl(opt_exec, p, NULL);

+#endif

+	dup2(saved_stderr, STDERR_FILENO);

+	err(1, "couldn't execute %s ", opt_exec);

+}

+

+/*

  * unix_connect()

  * Returns a socket connected to a local unix socket. Returns -1 on failure.

  */

@@ -705,6 +751,12 @@ readwrite(int nfd)

 	int lfd = fileno(stdout);

 	int plen;

+	if (opt_exec) {

+		if (vflag)

+			printf("Call sub-process %s\n", opt_exec);

+		execcmd(nfd);

+	}

+

 #ifdef HAVE_SO_JUMBO

 	plen = jflag ? 16384 : 2048;

 #else

@@ -968,7 +1020,7 @@ void

 usage(int ret)

 {

 	fprintf(stderr,

-	    "usage: netcat [-46DdhklnrtUuvz] [-I length] [-i interval] [-O length]\n"

+	    "usage: netcat [-46DdhklnrtUuvz] [-e cmd] [-I length] [-i interval] [-O length]\n"

 	    "              [-P proxy_username] [-p source_port] [-s source_ip_address] [-T ToS]\n"

 	    "              [-w timeout] [-X proxy_protocol]\n"

 	    "              [-x proxy_address[:port]] [hostname] [port]\n");