userspace: Implement `env` as an executable

userspace/programs/CMakeLists.txt

@@ -8,6 +8,7 @@ set(USERSPACE_PROGRAMS
 	dhcp-client
 	DynamicLoader
 	echo
+	env
 	getopt
 	http-server
 	id

userspace/programs/env/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(env ${SOURCES})
+banan_link_library(env ban)
+banan_link_library(env libc)
+
+install(TARGETS env OPTIONAL)

userspace/programs/env/main.cpp

@@ -0,0 +1,13 @@
+#include <stdio.h>
+
+extern char** environ;
+
+int main()
+{
+	if (!environ)
+		return 0;
+	char** current = environ;
+	while (*current)
+			printf("%s\n", *current++);
+	return 0;
+}