[fx] Add get-device and get-device-addr commands

Useful both for scripts and for interactive use (like in fx scp or
sftp).

Change-Id: I8bd3dc398b8fb0547dda44b3e8ca9ee4e3b923ec

tools/devshell/get-device

+#!/bin/bash
+# Copyright 2019 The Fuchsia Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+### print the current selected device name
+
+source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/vars.sh || exit $?
+
+get-device-name

tools/devshell/get-device-addr

+#!/bin/bash
+# Copyright 2019 The Fuchsia Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+### print the Fuchsia IPv6 address of the current selected device
+
+source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/vars.sh || exit $?
+fx-config-read
+
+get-fuchsia-device-addr

tools/devshell/scp

@@ -12,7 +12,7 @@
 ##
 ## Example usage:
 ##
-##   fx scp "[$(fx netaddr --fuchsia)]:source_file" dest_file
+##   fx scp "[$(fx get-device-addr)]:source_file" dest_file
 
 source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/vars.sh || exit $?
 fx-config-read

tools/devshell/sftp

@@ -13,7 +13,7 @@
 ##
 ## Example usage:
 ##
-##   fx sftp "[$(fx netaddr --fuchsia)]:source_file" dest_file
+##   fx sftp "[$(fx get-device-addr)]:source_file" dest_file
 
 source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/vars.sh || exit $?
 fx-config-read