telnet shell: Shell does not start with specified root command

[PhilBauknecht]

Hi,
I am trying to start the shell with another root command by using
CONFIG_SHELL_CMD_ROOT="authentication"
in the prj.conf file.

When I connect via UART everything works fine. Shell starts with the specified command.
But when I connect via telnet the shell starts with the standard root. I did not find any other config options to specify the telnet root command separately.

Is this a bug or am I getting something wrong?

Many thanks for your help on this issue and for the project itself - it's enjoyable to work with zephyr!

• I am using Zephyr version 3.6.99
• On a XMC45 relax kit from infineon

My whole *.conf file:

CONFIG_GPIO=y
CONFIG_PRINTK=y
CONFIG_SHELL=y

CONFIG_INIT_STACKS=y #This option instructs the kernel to initialize stack areas with a known value (0xaa) before they are first used, so that the high water mark can be easily determined. This applies to the stack areas for threads, as well as to the interrupt stack.

#logging stuff
CONFIG_LOG=y
CONFIG_LOG_MODE_DEFERRED=y
CONFIG_LOG_BUFFER_SIZE=1024
CONFIG_LOG_PRINTK=y
CONFIG_LOG_PROCESS_TRIGGER_THRESHOLD=0
CONFIG_LOG_TAG_MAX_LEN=8

#networking
CONFIG_NETWORKING=y
CONFIG_NET_IPV6=y
CONFIG_NET_IPV4=y
CONFIG_NET_ARP=y
CONFIG_NET_UDP=y
CONFIG_NET_TCP=y

CONFIG_NET_DHCPV4=n

CONFIG_NET_IF_UNICAST_IPV6_ADDR_COUNT=3
CONFIG_NET_IF_MCAST_IPV6_ADDR_COUNT=2
CONFIG_NET_MAX_CONTEXTS=10
CONFIG_NET_PKT_TX_COUNT=20
CONFIG_NET_BUF_TX_COUNT=50

CONFIG_NET_BUF_LOG=n
CONFIG_NET_LOG=n

CONFIG_NET_CONFIG_SETTINGS=y
CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8::1"
CONFIG_NET_CONFIG_MY_IPV4_ADDR="192.0.2.1"

CONFIG_NET_SHELL=y
CONFIG_KERNEL_SHELL=y
CONFIG_SHELL_BACKEND_TELNET=y
CONFIG_SHELL_TELNET_SUPPORT_COMMAND=y
#CONFIG_SHELL_TELNET_INIT_LOG_LEVEL=4


#set authentication as startup root command
CONFIG_SHELL_PROMPT_UART="auth: "
CONFIG_SHELL_CMD_ROOT="authentication"

[PhilBauknecht]

Hi, me again...

I answered the question myself. After going through the code I discovered that changing the root command during runtime affects all shell instances.

`shell_set_root_cmd("some_command");  `

-->

int shell_set_root_cmd(const char *cmd)
{
	const struct shell_static_entry *entry;

	entry = cmd ? root_cmd_find(cmd) : NULL;

	if (cmd && (entry == NULL)) {
		return -EINVAL;
	}

	STRUCT_SECTION_FOREACH(shell, sh) {
		sh->ctx->selected_cmd = entry;
	}

	return 0;
}

As we can see a FOREACH is used and that's why it affects all the shells.

Best regards

[PhilBauknecht]

Does anyone see an option to change the root command of only one shell?
A lot of others methods are shell specific (e.g. shell_prompt_change) but shell_set_root_cmd affects all shells :(

[PhilBauknecht]

Me again,
For anyone who is interested how I solved my issue:
When a shell command is defined the
SHELL_CMD_REGISTER
expands to
static const struct shell_static_entry _shell_authentication = [...]

The interesting part is that this command declares a
static const struct shell_static_entry
named
_shell_authentication .
This can be used to set the root command in a callback of a shell command via
shell->ctx->selected_cmd = &_shell_authentication;

This sets the root command to _shell_authentication only for the shell represented by shell.
shell_set_root_cmd sets the root command for ALL shells.

Now everything works fine and no matter which shell is used a login is needed.

Best regards.