Index: head/usr.bin/env/env.1
===================================================================
--- head/usr.bin/env/env.1
+++ head/usr.bin/env/env.1
@@ -31,7 +31,7 @@
 .\" From FreeBSD: src/usr.bin/printenv/printenv.1,v 1.17 2002/11/26 17:33:35 ru Exp
 .\" $FreeBSD$
 .\"
-.Dd April 17, 2008
+.Dd November 7, 2019
 .Dt ENV 1
 .Os
 .Sh NAME
@@ -39,7 +39,7 @@
 .Nd set environment and execute command, or print environment
 .Sh SYNOPSIS
 .Nm
-.Op Fl iv
+.Op Fl 0iv
 .Op Fl P Ar altpath
 .Op Fl S Ar string
 .Op Fl u Ar name
@@ -64,6 +64,8 @@
 .Pp
 The options are as follows:
 .Bl -tag -width indent
+.It Fl 0
+End each output line with NUL, not newline.
 .It Fl i
 Execute the
 .Ar utility
@@ -130,8 +132,15 @@
 .Ar utility
 is specified,
 .Nm
-prints out the names and values
-of the variables in the environment, with one name/value pair per line.
+prints out the names and values of the variables in the environment.
+Each name/value pair is separated by a new line unless
+.Fl 0
+is specified, in which case name/value pairs are separated by NUL.
+Both
+.Fl 0
+and
+.Ar utility
+may not be specified together.
 .\"
 .Ss Details of Fl S \&Ss (split-string) processing
 The processing of the
Index: head/usr.bin/env/env.c
===================================================================
--- head/usr.bin/env/env.c
+++ head/usr.bin/env/env.c
@@ -59,22 +59,33 @@
 
 static void usage(void);
 
+/*
+ * Exit codes.
+ */
+#define EXIT_CANCELED      125 /* Internal error prior to exec attempt. */
+#define EXIT_CANNOT_INVOKE 126 /* Program located, but not usable. */
+#define EXIT_ENOENT        127 /* Could not find program to exec. */
+
 int
 main(int argc, char **argv)
 {
-	char *altpath, **ep, *p, **parg;
+	char *altpath, **ep, *p, **parg, term;
 	char *cleanenv[1];
 	int ch, want_clear;
 	int rtrn;
 
 	altpath = NULL;
 	want_clear = 0;
-	while ((ch = getopt(argc, argv, "-iP:S:u:v")) != -1)
+	term = '\n';
+	while ((ch = getopt(argc, argv, "-0iP:S:u:v")) != -1)
 		switch(ch) {
 		case '-':
 		case 'i':
 			want_clear = 1;
 			break;
+		case '0':
+			term = '\0';
+			break;
 		case 'P':
 			altpath = strdup(optarg);
 			break;
@@ -118,6 +129,8 @@
 			err(EXIT_FAILURE, "setenv %s", *argv);
 	}
 	if (*argv) {
+		if (term == '\0')
+			errx(EXIT_CANCELED, "cannot specify command with -0");
 		if (altpath)
 			search_paths(altpath, argv);
 		if (env_verbosity) {
@@ -129,10 +142,11 @@
 				sleep(1);
 		}
 		execvp(*argv, argv);
-		err(errno == ENOENT ? 127 : 126, "%s", *argv);
+		err(errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE,
+		    "%s", *argv);
 	}
 	for (ep = environ; *ep; ep++)
-		(void)printf("%s\n", *ep);
+		(void)printf("%s%c", *ep, term);
 	exit(0);
 }
 
@@ -140,7 +154,7 @@
 usage(void)
 {
 	(void)fprintf(stderr,
-	    "usage: env [-iv] [-P utilpath] [-S string] [-u name]\n"
+	    "usage: env [-0iv] [-P utilpath] [-S string] [-u name]\n"
 	    "           [name=value ...] [utility [argument ...]]\n");
 	exit(1);
 }