examples/nanocoap_tool: add RIOT as a CLI tool

examples/nanocoap_tool/Makefile

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+# name of your application
+APPLICATION = nanocoap_tool
+
+# If no BOARD is found in the environment, use this default:
+BOARD ?= native
+
+# This has to be the absolute path to the RIOT base directory:
+RIOTBASE ?= $(CURDIR)/../..
+
+# Include packages that pull up and auto-init the link layer.
+USEMODULE += netdev_default
+USEMODULE += auto_init_gnrc_netif
+# Specify the mandatory networking modules for IPv6
+USEMODULE += gnrc_ipv6_default
+# Additional networking modules that can be dropped if not needed
+USEMODULE += gnrc_icmpv6_echo
+
+USEMODULE += auto_init_sock_dns    # add fall-back DNS server
+USEMODULE += sock_dns              # include DNS client
+USEMODULE += gnrc_ipv6_nib_dns     # include RDNSS option handling
+
+USEMODULE += nanocoap_sock
+USEMODULE += nanocoap_vfs
+
+USEMODULE += vfs_default
+
+USEMODULE += shell
+USEMODULE += shell_cmds_default
+
+# export the whole fs to RIOT
+CFLAGS += -DFS_NATIVE_DIR=\"/\"
+# mount it as '/' in RIOT to match the host
+CFLAGS += -DCONFIG_NATIVE_MOUNTPOINT=\"/\"
+# use the current working directory as download destination
+CFLAGS += -DCONFIG_NCGET_DEFAULT_DATA_DIR=\"/proc/self/cwd/\"
+
+# terminate RIOT with main()
+CFLAGS += -DCONFIG_CORE_EXIT_WITH_MAIN=1
+# don't be verbose
+CFLAGS += -DCONFIG_SKIP_BOOT_MSG=1
+
+RIOT_TERMINAL = native
+BOARD_WHITELIST = native native64
+
+DEVELHELP ?= 1
+
+include $(RIOTBASE)/Makefile.include

examples/nanocoap_tool/main.c

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+/*
+ * Copyright (C) 2024 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     examples
+ * @{
+ *
+ * @file
+ * @brief       Example application to access RIOT shell commands from Linux
+ *
+ * @author      Benjamin Valentin <[email protected]>
+ *
+ * @}
+ */
+
+#include <errno.h>
+#include "shell.h"
+#include "ztimer.h"
+
+int main(int argc, char **argv)
+{
+    if (argc < 1) {
+        printf("usage: <command> [args]\n");
+        return 0;
+    }
+
+    shell_command_handler_t handler = shell_find_handler(NULL, argv[0]);
+    if (handler == NULL) {
+        return -EINVAL;
+    }
+
+    /* wait some time for the network to be ready */
+    ztimer_sleep(ZTIMER_MSEC, 1000);
+
+    msg_t msg_queue[8];
+    msg_init_queue(msg_queue, ARRAY_SIZE(msg_queue));
+
+    return handler(argc, argv);
+}