Configuration Settings

The availability of the above commands depends upon features that may or may not be enabled in the NuttX configuration file. The following cmdtable indicates the dependency of each command on NuttX configuration settings. General configuration settings are discussed in the NuttX Porting Guide. Configuration settings specific to NSH as discussed at the cmdbottom of this document.

Note that in addition to general NuttX configuration settings, each NSH command can be individually disabled via the settings in the rightmost column. All of these settings make the configuration of NSH potentially complex but also allow it to squeeze into very small memory footprints.

Command Dependencies on Configuration Settings

Command	Depends on Configuration	Can Be Disabled with
[	! CONFIG_NSH_DISABLESCRIPT	CONFIG_NSH_DISABLE_TEST
Add a Routing Table Entry (addroute)	CONFIG_NET && CONFIG_NET_ROUTE	CONFIG_NSH_DISABLE_ADDROUTE
Access the ARP table (arp)	CONFIG_NET && CONFIG_NET_ARP	CONFIG_NSH_DISABLE_ARP
Base64 Decode (base64dec)	CONFIG_NETUTILS_CODECS && CONFIG_CODECS_BASE64	CONFIG_NSH_DISABLE_BASE64DEC
Base64 Encode (base64enc)	CONFIG_NETUTILS_CODECS && CONFIG_CODECS_BASE64	CONFIG_NSH_DISABLE_BASE64ENC
Extract Base File/Directory Name (basename)	.	CONFIG_NSH_DISABLE_BASENAME
Terminate a Loop (break)	! CONFIG_NSH_DISABLESCRIPT && ! CONFIG_NSH_DISABLE_LOOPS	.
Concatenate Files (cat)	CONFIG_NSH_DISABLE_CAT	.
Change Current Working Directory (cd)	! CONFIG_DISABLE_ENVIRON	CONFIG_NSH_DISABLE_CD
Compare Files (cmp)	CONFIG_NSH_DISABLE_CMP	.
Copy Files (cp)	CONFIG_NSH_DISABLE_CP	.
Show or set the date and time (date)	CONFIG_NSH_DISABLE_DATE	.
Copy and Convert Files (dd)	CONFIG_NSH_DISABLE_DD	.
Delete a Routing Table Entry (delroute)	CONFIG_NET && CONFIG_NET_ROUTE	CONFIG_NSH_DISABLE_DELROUTE
Show Volume Status (df)	! CONFIG_DISABLE_MOUNTPOINT	CONFIG_NSH_DISABLE_DF
Extract Path to a File/Directory (dirname)	CONFIG_NSH_DISABLE_DIRNAME	.
Dump Buffered SYSLOG Output (dmesg)	CONFIG_RAMLOG_SYSLOG	CONFIG_NSH_DISABLE_DMESG
Echo Strings and Variables (echo)	CONFIG_NSH_DISABLE_ECHO	.
Show Environment Variables (env)	CONFIG_FS_PROCFS && ! CONFIG_DISABLE_ENVIRON && ! CONFIG_PROCFS_EXCLUDE_ENVIRON	CONFIG_NSH_DISABLE_ENV
Execute User Code (exec)	CONFIG_NSH_DISABLE_EXEC	.
Exit NSH (exit)	CONFIG_NSH_DISABLE_EXIT	.
Set an Environment Variable (export)	CONFIG_NSH_VARS && ! CONFIG_DISABLE_ENVIRON	CONFIG_NSH_DISABLE_EXPORT
Show Memory Manager Status (free)	CONFIG_NSH_DISABLE_FREE	.
Get File Via TFTP (get)	CONFIG_NET && CONFIG_NET_UDP && MTU >= 584	CONFIG_NSH_DISABLE_GET
Show Usage Command Usage (help) 6	CONFIG_NSH_DISABLE_HELP	.
Hexadecimal Dump of File or Device (hexdump)	CONFIG_NSH_DISABLE_HEXDUMP	.
Manage Network Configuration (ifconfig)	CONFIG_NET && CONFIG_FS_PROCFS && ! CONFIG_FS_PROCFS_EXCLUDE_NET	CONFIG_NSH_DISABLE_IFCONFIG
Take a network down (ifdown)	CONFIG_NET && CONFIG_FS_PROCFS && ! CONFIG_FS_PROCFS_EXCLUDE_NET	CONFIG_NSH_DISABLE_IFUPDOWN
Bring a network up (ifup)	CONFIG_NET && CONFIG_FS_PROCFS && ! CONFIG_FS_PROCFS_EXCLUDE_NET	CONFIG_NSH_DISABLE_IFUPDOWN
Install an OS module (insmod)	CONFIG_MODULE	CONFIG_NSH_DISABLE_MODCMDS
Show Interrupt Status (irqinfo)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_FS_PROCFS && CONFIG_SCHED_IRQMONITOR	.
Send a signal to a task (kill)	CONFIG_NSH_DISABLE_KILL	.
Setup/teardown the Loop Device (losetup)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_DEV_LOOP	CONFIG_NSH_DISABLE_LOSETUP
Link to a File or Directory (ln)	CONFIG_PSEUDOFS_SOFTLINKS	CONFIG_NSH_DISABLE_LN
List Directory Contents (ls)	CONFIG_NSH_DISABLE_LS	.
Show information about installed OS modules (lsmod)	CONFIG_MODULE && CONFIG_FS_PROCFS && ! CONFIG_FS_PROCFS_EXCLUDE_MODULE	CONFIG_NSH_DISABLE_MODCMDS
Calculate MD5 (md5)	CONFIG_NETUTILS_CODECS && CONFIG_CODECS_HASH_MD5	CONFIG_NSH_DISABLE_MD5
Access Memory (mb, mh, and mw)	.	CONFIG_NSH_DISABLE_MB, CONFIG_NSH_DISABLE_MH, CONFIG_NSH_DISABLE_MW
Create a Directory (mkdir)	(! CONFIG_DISABLE_MOUNTPOINT || ! CONFIG_DISABLE_PSEUDOFS_OPERATIONS)	CONFIG_NSH_DISABLE_MKDIR
Create a FAT File System (mkfatfs)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_FSUTILS_MKFATFS	CONFIG_NSH_DISABLE_MKFATFS
Create a FIFO (mkfifo)	CONFIG_PIPES && CONFIG_DEV_FIFO_SIZE > 0	CONFIG_NSH_DISABLE_MKFIFO
Create a RAMDISK (mkrd)	! CONFIG_DISABLE_MOUNTPOINT	CONFIG_NSH_DISABLE_MKRD
Mount a File System (mount)	! CONFIG_DISABLE_MOUNTPOINT	CONFIG_NSH_DISABLE_MOUNT
Rename a File (mv)	! CONFIG_DISABLE_MOUNTPOINT || ! CONFIG_DISABLE_PSEUDOFS_OPERATIONS	CONFIG_NSH_DISABLE_MV
Mount an NFS file system (nfsmount)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_NET && CONFIG_NFS	CONFIG_NSH_DISABLE_NFSMOUNT
Lookup a network address (nslookup)	CONFIG_LIBC_NETDB && CONFIG_NETDB_DNSCLIENT	CONFIG_NSH_DISABLE_NSLOOKUP
Change a User’s Password (passwd)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_NSH_LOGIN_PASSWD	CONFIG_NSH_DISABLE_PASSWD
Manage Power Management Subsystem (pmconfig)	CONFIG_PM	CONFIG_NSH_DISABLE_PMCONFIG
Shut the system down (poweroff)	CONFIG_BOARDCTL_POWEROFF	CONFIG_NSH_DISABLE_POWEROFF
Show Current Tasks and Threads (ps)	CONFIG_FS_PROCFS && ! CONFIG_FS_PROCFS_EXCLUDE_PROC	CONFIG_NSH_DISABLE_PS
Send File Via TFTP (put)	CONFIG_NET && CONFIG_NET_UDP && MTU >= 558 4, 5	CONFIG_NSH_DISABLE_PUT
Show Current Working Directory (pwd)	! CONFIG_DISABLE_ENVIRON	CONFIG_NSH_DISABLE_PWD
Show target of a link (readlink)	CONFIG_PSEUDOFS_SOFTLINKS	CONFIG_NSH_DISABLE_READLINK
Reboot the system (reboot)	CONFIG_BOARD_RESET	CONFIG_NSH_DISABLE_REBOOT
Remove a File (rm)	! CONFIG_DISABLE_MOUNTPOINT || ! CONFIG_DISABLE_PSEUDOFS_OPERATIONS	CONFIG_NSH_DISABLE_RM
Remove a Directory (rmdir)	! CONFIG_DISABLE_MOUNTPOINT |! CONFIG_DISABLE_PSEUDOFS_OPERATIONS	CONFIG_NSH_DISABLE_RMDIR
Remove on OS Module (rmmod)	CONFIG_MODULE	CONFIG_NSH_DISABLE_MODCMDS
Show routing table (route)	CONFIG_FS_PROCFS && CONFIG_FS_PROCFS_EXCLUDE_NET && ! CONFIG_FS_PROCFS_EXCLUDE_ROUTE && CONFIG_NET_ROUTE && ! CONFIG_NSH_DISABLE_ROUTE && (CONFIG_NET_IPv4 |CONFIG_NET_IPv6)	CONFIG_NSH_DISABLE_ROUTE
Start/Stop the OpenAMP RPC Tunnel (rptun)	CONFIG_RPTUN	CONFIG_NSH_DISABLE_RPTUN
Set a Variable (set)	CONFIG_NSH_VARS || ! CONFIG_DISABLE_ENVIRON	CONFIG_NSH_DISABLE_SET
Shut the system down (shutdown)	CONFIG_BOARDCTL_POWEROFF || CONFIG_BOARD_RESET	CONFIG_NSH_DISABLE_SHUTDOWN
Wait for Seconds (sleep)	.	CONFIG_NSH_DISABLE_SLEEP
cmdsource	CONFIG_FILE_STREAM && ! CONFIG_NSH_DISABLESCRIPT	CONFIG_NSH_DISABLE_SOURCE
Time Start the Telnet Daemon (telnetd)	CONFIG_NSH_TELNET && CONFIG_SYSTEM_TELNETD
Evaluate Expression (test)	! CONFIG_NSH_DISABLESCRIPT	CONFIG_NSH_DISABLE_TEST
Time execution of another command (time)	.	CONFIG_NSH_DISABLE_TIME
Set the Size of a File (truncate)	! CONFIG_DISABLE_MOUNTPOINT	CONFIG_NSH_DISABLE_TRUNCATE
Unmount a File System (umount)	! CONFIG_DISABLE_MOUNTPOINT	CONFIG_NSH_DISABLE_UMOUNT
Print system information (uname)	.	CONFIG_NSH_DISABLE_UNAME
Unset an Environment Variable (unset)	CONFIG_NSH_VARS || ! CONFIG_DISABLE_ENVIRON	CONFIG_NSH_DISABLE_UNSET
URL Decode (urldecode)	! CONFIG_NETUTILS_CODECS && CONFIG_CODECS_URLCODE	CONFIG_NSH_DISABLE_URLDECODE
URL Encode (urlencode)	! CONFIG_NETUTILS_CODECS && CONFIG_CODECS_URLCODE	CONFIG_NSH_DISABLE_URLENCODE
Add a New User (useradd)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_NSH_LOGIN_PASSWD	CONFIG_NSH_DISABLE_USERADD
Delete a user (userdel)	! CONFIG_DISABLE_MOUNTPOINT && CONFIG_NSH_LOGIN_PASSWD	CONFIG_NSH_DISABLE_USERDEL
Wait for Microseconds (usleep)	.	CONFIG_NSH_DISABLE_USLEEP
Get File Via HTTP (wget)	CONFIG_NET && CONFIG_NET_TCP	CONFIG_NSH_DISABLE_WGET
Hexadecimal Dump of Memory (xd)	.	CONFIG_NSH_DISABLE_XD

4(1,2)

Because of hardware padding, the actual required packet size may be larger

5

Special TFTP server start-up options will probably be required to permit creation of files for the correct operation of the put command.

6

Verbose help output can be suppressed by defining CONFIG_NSH_HELP_TERSE. In that case, the help command is still available but will be slightly smaller.

Built-In Command Dependencies on Configuration Settings

All built-in applications require that support for NSH built-in applications has been enabled. This support is enabled with CONFIG_BUILTIN=y and CONFIG_NSH_BUILTIN_APPS=y.

Command	Depends on Configuration
ping	CONFIG_NET && CONFIG_NET_ICMP && CONFIG_NET_ICMP_SOCKET && CONFIG_SYSTEM_PING
ping6	CONFIG_NET && CONFIG_NET_ICMPv6 && CONFIG_NET_ICMPv6_SOCKET && CONFIG_SYSTEM_PING6

NSH-Specific Configuration Settings

The behavior of NSH can be modified with the following settings in the boards/<arch>/<chip>/<board>/defconfig file:

Configuration	Description
CONFIG_NSH_READLINE	Selects the minimal implementation of readline(). This minimal implementation provides on backspace for command line editing. It expects some minimal VT100 command support from the terminal.
CONFIG_NSH_CLE	Selects the more extensive, EMACS-like command line editor. Select this option only if (1) you don’t mind a modest increase in the FLASH footprint, and (2) you work with a terminal that supports extensive VT100 editing commands. Selecting this option will add probably 1.5-2KB to the FLASH footprint.
CONFIG_NSH_BUILTIN_APPS	Support external registered, “builtin” applications that can be executed from the NSH command line (see apps/README.txt for more information). This required CONFIG_BUILTIN to enable NuttX support for “builtin” applications.
CONFIG_NSH_FILEIOSIZE	Size of a static I/O buffer used for file access (ignored if there is no file system). Default is 1024.
CONFIG_NSH_STRERROR	strerror(errno) makes more readable output but strerror() is very large and will not be used unless this setting is y. This setting depends upon the strerror() having been enabled with CONFIG_LIBC_STRERROR.
CONFIG_NSH_LINELEN	The maximum length of one command line and of one output line. Default: 80
CONFIG_NSH_DISABLE_SEMICOLON	By default, you can enter multiple NSH commands on a line with each command separated by a semicolon. You can disable this feature to save a little memory on FLASH challenged platforms. Default: n
CONFIG_NSH_CMDPARMS	If selected, then the output from commands, from file applications, and from NSH built-in commands can be used as arguments to other commands. The entity to be executed is identified by enclosing the command line in back quotes. For example: set FOO `myprogram $BAR` will execute the program named myprogram passing it the value of the environment variable BAR. The value of the environment variable FOO is then set output of myprogram on stdout. Because this feature commits significant resources, it is disabled by default. The CONFIG_NSH_CMDPARMS interim output will be retained in a temporary file. Full path to a directory where temporary files can be created is taken from CONFIG_LIBC_TMPDIR and it defaults to /tmp if CONFIG_LIBC_TMPDIR is not set.
CONFIG_NSH_MAXARGUMENTS	The maximum number of NSH command arguments. Default: 6
CONFIG_NSH_ARGCAT	Support concatenation of strings with environment variables or command output. For example: set FOO XYZ set BAR 123 set FOOBAR ABC_${FOO}_${BAR} would set the environment variable FOO to XYZ, BAR to 123 and FOOBAR to ABC_XYZ_123. If CONFIG_NSH_ARGCAT is not selected, then a slightly small FLASH footprint results but then also only simple environment variables like $FOO can be used on the command line.
CONFIG_NSH_VARS	By default, there are no internal NSH variables. NSH will use OS environment variables for all variable storage. If this option, NSH will also support local NSH variables. These variables are, for the most part, transparent and work just like the OS environment variables. The difference is that when you create new tasks, all of environment variables are inherited by the created tasks. NSH local variables are not. If this option is enabled (and CONFIG_DISABLE_ENVIRON is not), then a new command called ‘export’ is enabled. The export command works very must like the set command except that is operates on environment variables. When CONFIG_NSH_VARS is enabled, there are changes in the behavior of certain commands. See following cmdtable.
CONFIG_NSH_QUOTE	Enables back-slash quoting of certain characters within the command. This option is useful for the case where an NSH script is used to dynamically generate a new NSH script. In that case, commands must be treated as simple text strings without interpretation of any special characters. Special characters such as $, `, ", and others must be retained intact as part of the test string. This option is currently only available is CONFIG_NSH_ARGCAT is also selected.
CONFIG_NSH_NESTDEPTH	The maximum number of nested if-then[-else]-fi <#conditional>`__ sequences that are permissible. Default: 3
CONFIG_NSH_DISABLESCRIPT	This can be set to y to suppress support for scripting. This setting disables the `sh <#cmdsh>`__, `test <#cmdtest>`__, and `[ <#cmtest>`__ commands and the `if-then[-else]-fi <#conditional>`__ construct. This would only be set on systems where a minimal footprint is a necessity and scripting is not.
CONFIG_NSH_DISABLE_ITEF	If scripting is enabled, then then this option can be selected to suppress support for if-then-else-fi sequences in scripts. This would only be set on systems where some minimal scripting is required but if-then-else-fi is not.
CONFIG_NSH_DISABLE_LOOPS	If scripting is enabled, then then this option can be selected suppress support for while-do-done and until-do-done sequences in scripts. This would only be set on systems where some minimal scripting is required but looping is not.
CONFIG_NSH_DISABLEBG	This can be set to y to suppress support for background commands. This setting disables the `nice <#cmdoverview>`__ command prefix and the `& <#cmdoverview>`__ command suffix. This would only be set on systems where a minimal footprint is a necessity and background command execution is not.
CONFIG_NSH_MMCSDMINOR	If the architecture supports an MMC/SD slot and if the NSH architecture specific logic is present, this option will provide the MMC/SD minor number, i.e., the MMC/SD block driver will be registered as /dev/mmcsdN where N is the minor number. Default is zero.
CONFIG_NSH_ROMFSETC	Mount a ROMFS file system at /etc and provide a system init script at /etc/init.d.rc.sysinit and a startup script at /etc/init.d/rcS. The default system init script will mount a FAT FS RAMDISK at /tmp but the logic is easily extensible.
CONFIG_NSH_CONSOLE	If CONFIG_NSH_CONSOLE is set to y, then a serial console front-end is selected. Normally, the serial console device is a UART and RS-232 interface. However, if CONFIG_USBDEV is defined, then a USB serial device may, instead, be used if the one of the following are defined: CONFIG_PL2303 and CONFIG_PL2303_CONSOLE. Sets up the Prolifics PL2303 emulation as a console device at /dev/console. CONFIG_CDCACM and CONFIG_CDCACM_CONSOLE. Sets up the CDC/ACM serial device as a console device at /dev/console. CONFIG_NSH_USBCONSOLE. If defined, then an arbitrary USB device may be used to as the NSH console. In this case, CONFIG_NSH_USBCONDEV must be defined to indicate which USB device to use as the console. The advantage of using a device other that /dev/console is that normal debug output can then use /dev/console while NSH uses CONFIG_NSH_USBCONDEV. CONFIG_NSH_USBCONDEV. If CONFIG_NSH_USBCONSOLE is set to ‘y’, then CONFIG_NSH_USBCONDEV must also be set to select the USB device used to support the NSH console. This should be set to the quoted name of a readable/write-able USB driver such as: CONFIG_NSH_USBCONDEV="/dev/ttyACM0". If there are more than one USB slots, then a USB device minor number may also need to be provided: CONFIG_NSH_UBSDEV_MINOR: The minor device number of the USB device. Default: 0 If USB tracing is enabled (CONFIG_USBDEV_TRACE), then NSH will initialize USB tracing as requested by the following. Default: Only USB errors are traced. CONFIG_NSH_USBDEV_TRACEINIT: Show initialization events CONFIG_NSH_USBDEV_TRACECLASS: Show class driver events CONFIG_NSH_USBDEV_TRACETRANSFERS: Show data transfer events CONFIG_NSH_USBDEV_TRACECONTROLLER: Show controller events CONFIG_NSH_USBDEV_TRACEINTERRUPTS: Show interrupt-related events.
CONFIG_NSH_ALTCONDEV and	If CONFIG_NSH_CONSOLE is set CONFIG_NSH_CONDEV to y, then CONFIG_NSH_ALTCONDEV may also be selected to enable use of an alternate character device to support the NSH console. If CONFIG_NSH_ALTCONDEV is selected, then CONFIG_NSH_CONDEV holds the quoted name of a readable/write-able character driver such as: CONFIG_NSH_CONDEV="/dev/ttyS1". This is useful, for example, to separate the NSH command line from the system console when the system console is used to provide debug output. Default: stdin and stdout (probably “/dev/console”) NOTE 1: When any other device other than /dev/console is used for a user interface, (1) linefeeds (\n) will not be expanded to carriage return / linefeeds (\r\n). You will need to configure your terminal program to account for this. And (2) input is not automatically echoed so you will have to turn local echo on. NOTE 2: This option forces the console of all sessions to use NSH_CONDEV. Hence, this option only makes sense for a system that supports only a single session. This option is, in particular, incompatible with Telnet sessions because each Telnet session must use a different console device.
CONFIG_NSH_TELNET	If CONFIG_NSH_TELNET is set to y, then a TELNET server front-end is selected. When this option is provided, you may log into NuttX remotely using telnet in order to access NSH.
CONFIG_NSH_ARCHINIT	Set CONFIG_NSH_ARCHINIT if your board provides architecture specific initialization via the board-specific function board_app_initialize(). This function will be called early in NSH initialization to allow board logic to do such things as configure MMC/SD slots.

CMD	w/o CONFIG_NSH_VARS	w/CONFIG_NSH_VARS
set <a> <b>	Set environment variable <a> to <b>	Set NSH variable <a> to <b> (Unless the NSH variable has been promoted via export, in which case the env ironment variable of the same name is set to <b>).
set	Causes an error.	Lists all NSH variables.
unset <a>	Unsets environment variable <a>	Unsets both environment variable and NSH variable with and name <a>
export <a> <b>	Causes an error,	Unsets NSH variable <a>. Sets environment variable <a> to <b>.
export <a>	Causes an error.	Sets environment variable <a> to the value of NSH variable <a> (or “” if the NSH variable has not been set). Unsets NSH local variable <a>.
env	Lists all environment variables	Lists all environment variables (only)

If Telnet is selected for the NSH console, then we must configure the resources used by the Telnet daemon and by the Telnet clients.

Configuration	Description
CONFIG_SYSTEM_TELNETD_PORT	The telnet daemon will listen on this TCP port number for connections. Default: 23
CONFIG_SYSTEM_TELNETD_PRIORITY	Priority of the Telnet daemon. Default: SCHED_PRIORITY_DEFAULT
CONFIG_SYSTEM_TELNETD_STACKSIZE	Stack size allocated for the Telnet daemon. Default: 2048
CONFIG_SYSTEM_TELNETD_SESSION_PRIORITY	Priority of the Telnet client. Default: SCHED_PRIORITY_DEFAULT
CONFIG_SYSTEM_TELNETD_SESSION_STACKSIZE	Stack size allocated for the Telnet client. Default: 2048

One or both of CONFIG_NSH_CONSOLE and CONFIG_NSH_TELNET must be defined. If CONFIG_NSH_TELNET is selected, then there some other configuration settings that apply:

Configuration	Description
CONFIG_NET=y	Of course, networking must be enabled.
CONFIG_NET_TCP=y	TCP/IP support is required for telnet (as well as various other TCP-related configuration settings).
CONFIG_NSH_DHCPC	Obtain the IP address via DHCP.
CONFIG_NSH_IPADDR	If CONFIG_NSH_DHCPC is NOT set, then the static IP address must be provided.
CONFIG_NSH_DRIPADDR	Default router IP address
CONFIG_NSH_NETMASK	Network mask
CONFIG_NSH_NOMAC	Set if your Ethernet hardware has no built-in MAC address. If set, a bogus MAC will be assigned.
CONFIG_NSH_MAX_ROUNDTRIP	This is the maximum round trip for a response to a ICMP ECHO request. It is in units of deciseconds. The default is 20 (2 seconds).

If you use DHCPC, then some special configuration network options are required. These include:

Configuration	Description
CONFIG_NET=y	Of course, networking must be enabled.
CONFIG_NET_UDP=y	UDP support is required for DHCP (as well as various other UDP-related configuration settings).
CONFIG_NET_BROADCAST=y	UDP broadcast support is needed.
CONFIG_NET_ETH_PKTSIZE=650 (or larger)	Per RFC2131 (p. 9), the DHCP client must be prepared to receive DHCP messages of up to 576 bytes (excluding Ethernet, IP, or UDP headers and FCS). NOTE: Note that the actual MTU setting will depend upon the specific link protocol. Here Ethernet is indicated.

If CONFIG_NSH_ROMFSETC is selected, then the following additional configuration setting apply:

Configuration	Description
CONFIG_NSH_ARCHROMFS	May be defined to specify an alternative ROMFS image that can be found at boards/<arch>/<chip>/<board>/include/nsh_romfsimg.h.
CONFIG_NSH_ROMFSMOUNTPT	The default mountpoint for the ROMFS volume is "/etc", but that can be changed with this setting. This must be a absolute path beginning with ‘/’ and enclosed in quotes.
CONFIG_NSH_SYSINITSCRIPT	This is the relative path to the system init script within the mountpoint. The default is "init.d/rc.sysinit". This is a relative path and must not start with ‘/’ but must be enclosed in quotes.
CONFIG_NSH_INITSCRIPT	This is the relative path to the startup script within the mountpoint. The default is "init.d/rcS". This is a relative path and must not start with ‘/’ but must be enclosed in quotes.
CONFIG_NSH_ROMFSDEVNO	This is the minor number of the ROMFS block device. The default is ‘0’ corresponding to /dev/ram0.
CONFIG_NSH_ROMFSSECTSIZE	This is the sector size to use with the ROMFS volume. Since the default volume is very small, this defaults to 64 but should be increased if the ROMFS volume were to be become large. Any value selected must be a power of 2.

When the default rc.sysinit file used when CONFIG_NSH_ROMFSETC is selected, it will mount a FAT FS under /tmp. The following selections describe that FAT FS.

Configuration	Description
CONFIG_NSH_FATDEVNO	This is the minor number of the FAT FS block device. The default is ‘1’ corresponding to /dev/ram1.
CONFIG_NSH_FATSECTSIZE	This is the sector size use with the FAT FS. Default is 512.