Fotis Panagiotopoulos 6daec61423 Typo fix.

2022-01-28 00:02:08 +08:00

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`nshlib` NuttShell (NSH)

This directory contains the NuttShell (NSH) library. This library can be linked with other logic to provide a simple shell application for NuttX.

Console/NSH Front End
Command Overview
Conditional Command Execution
Looping
Built-In Variables
Current Working Directory
- Environment Variables
NSH Start-Up Script
Simple Commands
Built-In Applications
NSH Configuration Settings
- Command Dependencies on Configuration Settings
- Built-in Application Configuration Settings
- NSH-Specific Configuration Settings
Common Problems

Console / NSH Front End

Using settings in the configuration file, NSH may be configured to use either the serial stdin/out or a telnet connection as the console or BOTH. When NSH is started, you will see the following welcome on either console:

NuttShell (NSH)
nsh>

nsh> is the NSH prompt and indicates that you may enter a command from the console.

Command Overview

This directory contains the NuttShell (NSH). This is a simple shell-like application. At present, NSH supports the following commands forms:

Simple command:
```
<cmd>
```
Command with re-directed output:
```
<cmd> > <file>
<cmd> >> <file>
```
Background command:
```
<cmd> &
```
Re-directed background command:
```
<cmd> > <file> &
<cmd> >> <file> &
```

Where:

<cmd> - is any one of the simple commands listed later.
<file> - is the full or relative path to any writeable object in the file system name space (file or character driver). Such objects will be referred to simply as files throughout this README.

NSH executes at the mid-priority (128). Backgrounded commands can be made to execute at higher or lower priorities using nice:

[nice [-d <niceness>>]] <cmd> [> <file>|>> <file>] [&]

Where <niceness> is any value between -20 and 19 where lower (more negative values) correspond to higher priorities. The default niceness is 10.

Multiple commands per line. NSH will accept multiple commands per command line with each command separated with the semi-colon character (;).

If CONFIG_NSH_CMDPARMS is 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.

If CONFIG_NSH_ARGCAT is selected, the 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 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_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.

Conditional Command Execution

An if-then[-else]-fi construct is also supported in order to support conditional execution of commands. This works from the command line but is primarily intended for use within NSH scripts (see the sh command). The syntax is as follows:

if [!] <cmd>
then
  [sequence of <cmd>]
else
  [sequence of <cmd>]
fi

Looping

while-do-done and until-do-done looping constructs are also supported. These works from the command line but are primarily intended for use within NSH scripts (see the sh command). The syntax is as follows:

while <test-cmd>; do <cmd-sequence>; done

(Execute <cmd-sequence> as long as <test-cmd> has an exit status of zero.)

until <test-cmd>; do <cmd-sequence>; done

(Execute <cmd-sequence> as long as <test-cmd> has a non-zero exit status.)

A break command is also supported. The break command is only meaningful within the body of the a while or until loop, between the do and done tokens. If the break command is executed within the body of a loop, the loop will immediately terminate and execution will continue with the next command immediately following the done token.

Built-In Variables

$? - The result of the last simple command execution.

Current Working Directory

All path arguments to commands may be either an absolute path or a path relative to the current working directory. The current working directory is set using the cd command and can be queried either by using the pwd command or by using the echo $PWD command.

Environment Variables:

PWD - The current working directory
OLDPWD - The previous working directory

NSH Start-Up Script

NSH supports options to provide a start up script for NSH. In general this capability is enabled with CONFIG_NSH_ROMFSETC, but has several other related configuration options as described in the final section of this README. This capability also depends on:

CONFIG_DISABLE_MOUNTPOINT not set
CONFIG_FS_ROMFS

Default Start-Up Behavior

The implementation that is provided is intended to provide great flexibility for the use of Start-Up files. This paragraph will discuss the general behavior when all of the configuration options are set to the default values.

In this default case, enabling CONFIG_NSH_ROMFSETC will cause NSH to behave as follows at NSH startup time:

NSH will create a read-only RAM disk (a ROM disk), containing a tiny ROMFS file system containing the following:
```
 |   `--init.d/
         `-- rcS
```
Where rcS is the NSH start-up script

NSH will then mount the ROMFS file system at /etc, resulting in:

 |--dev/
 |   `-- ram0
 `--etc/
     `--init.d/
         `-- rcS

By default, the contents of rcS script are:

# Create a RAMDISK and mount it at XXXRDMOUNTPOINTXXX

mkrd -m 1 -s 512 1024
mkfatfs /dev/ram1
mount -t vfat /dev/ram1 /tmp

NSH will execute the script at /etc/init.d/rcS at start-up (before the first NSH prompt. After execution of the script, the root FS will look like:
```
 |--dev/
 |   |-- ram0
 |   `-- ram1
 |--etc/
 |   `--init.d/
 |       `-- rcS
 `--tmp/
```

Modifying the ROMFS Image

The contents of the /etc directory are retained in the file apps/nshlib/nsh_romfsimg.h (OR, if CONFIG_NSH_ARCHROMFS is defined, include/arch/board/rcS.template). In order to modify the start-up behavior, there are three things to study:

Configuration Options. The additional CONFIG_NSH_ROMFSETC configuration options discussed in the final section of this README.
tools/mkromfsimg.sh Script. The script tools/mkromfsimg.sh creates nsh_romfsimg.h. It is not automatically executed. If you want to change the configuration settings associated with creating and mounting the /tmp directory, then it will be necessary to re-generate this header file using the mkromfsimg.sh script.

The behavior of this script depends upon three things:
- The configuration settings of the installed NuttX configuration.
- The genromfs tool (available from http://romfs.sourceforge.net).
- The file apps/nshlib/rcS.template (OR, if CONFIG_NSH_ARCHROMFS is defined, include/arch/board/rcs.template)
rcS.template. The file apps/nshlib/rcS.template contains the general form of the rcS file; configured values are plugged into this template file to produce the final rcS file.

Note: apps/nshlib/rcS.template generates the standard, default nsh_romfsimg.h file. If CONFIG_NSH_ARCHROMFS is defined in the NuttX configuration file, then a custom, board-specific nsh_romfsimg.h file residing in boards/<arch>/<chip>/<board>/include will be used. Note when the OS is configured, include/arch/board will be linked to boards/<arch>/<chip>/<board>/include.

All of the startup-behavior is contained in rcS.template. The role of mkromfsimg.sh is to (1) apply the specific configuration settings to rcS.template to create the final rcS, and (2) to generate the header file nsh_romfsimg.h containing the ROMFS file system image.

Simple Commands

[ <expression> ] test <expression>

These are two alternative forms of the same command. They support evaluation of a boolean expression which sets $?. This command is used most frequently as the conditional command following the if in the if-then[-else]-fi construct.

Expression Syntax:

expression = simple-expression | !expression |
             expression -o expression | expression -a expression

simple-expression = unary-expression | binary-expression

unary-expression = string-unary | file-unary

string-unary = -n string | -z string

file-unary = -b file | -c file | -d file | -e file | -f file |
             -r file | -s file | -w file

binary-expression = string-binary | numeric-binary

string-binary = string = string | string == string | string != string

numeric-binary = integer -eq integer | integer -ge integer |
                 integer -gt integer | integer -le integer |
                 integer -lt integer | integer -ne integer

addroute <target> [<netmask>] <router> addroute default <ipaddr> <interface>

This command adds an entry in the routing table. The new entry will map the IP address of a router on a local network(<router>) to an external network characterized by the <target> IP address and a network mask <netmask>

The netmask may also be expressed using IPv4 CIDR or IPv6 slash notation. In that case, the netmask need not be provided.

Example:
```
nsh> addroute 11.0.0.0 255.255.255.0 10.0.0.2
```
which is equivalent to
```
nsh> addroute 11.0.0.0/24 10.0.0.2
```
The second form of the addroute command can be used to set the default gateway.
arp [-t|-a <ipaddr>|-d <ipaddr>|-s <ipaddr> <hwaddr>]

Access the OS ARP table.
- -a <ipaddr> Will show the hardware address that the IP address <ipaddr> is mapped to.
- -d <ipaddr> Will delete the mapping for the IP address <ipaddr> from the ARP table.
- -s <ipaddr> <hwaddr> Will set (or replace) the mapping of the IP address <ipaddr> to the hardware address <hwaddr>.
- -t Will dump the entire content of the ARP table. This option is only available if CONFIG_NETLINK_ROUTE is enabled.
Example:
```
nsh> arp -a 10.0.0.1
nsh: arp: no such ARP entry: 10.0.0.1

nsh> arp -s 10.0.0.1 00:13:3b:12:73:e6
nsh> arp -a 10.0.0.1
HWAddr: 00:13:3b:12:73:e6

nsh> arp -d 10.0.0.1
nsh> arp -a 10.0.0.1
nsh: arp: no such ARP entry: 10.0.0.1
```
base64dec [-w] [-f] <string or filepath>
base64dec [-w] [-f] <string or filepath>
basename <path> [<suffix>]

Extract the final string from a <path> by removing the preceding path segments and (optionally) removing any trailing <suffix>.
break

The break command is only meaningful within the body of the a while or until loop, between the do and done tokens. Outside of a loop, break command does nothing. If the break command is executed within the body of a loop, the loop will immediately terminate and execution will continue with the next command immediately following the done token.
cat <path> [<path> [<path> ...]]

This command copies and concatenates all of the files at <path> to the console (or to another file if the output is redirected).
cd [<dir-path>|-|~|..]

Changes the current working directory (PWD). Also sets the previous working directory environment variable (OLDPWD).

Forms:
- cd <dir-path> sets the current working directory to <dir-path>.
- cd - sets the current working directory to the previous working directory ($OLDPWD). Equivalent to cd $OLDPWD.
- cd or cd ~ set the current working directory to the home directory. The home directory can be configured by setting CONFIG_LIBC_HOMEDIR in the configuration file. The default home directory is /.
- cd .. sets the current working directory to the parent directory.
cmp <path1> <path2>

Compare of the contents of the file at <file1> with the contents of the file at <path2>. Returns an indication only if the files differ.
cp <source-path> <dest-path>

Copy of the contents of the file at <source-path> to the location in the file system indicated by <path-path>
date [-s "MMM DD HH:MM:SS YYYY"] [-u]

Show or set the current date and time.

Only one format is used both on display and when setting the date/time: MMM DD HH:MM:SS YYYY. For example,
```
data -s "Sep 1 11:30:00 2011"
```
24-hour time format is assumed.
dd if=<infile> of=<outfile> [bs=<sectsize>] [count=<sectors>] [skip=<sectors>]

Copy blocks from <infile> to <outfile>. <nfile> or <outfile> may be the path to a standard file, a character device, or a block device.

Examples:
1. Read from character device, write to regular file. This will create a new file of the specified size filled with zero.
```
nsh> dd if=/dev/zero of=/tmp/zeros bs=64 count=16
nsh> ls -l /tmp
/tmp:
-rw-rw-rw-    1024 ZEROS
```
2. Read from character device, write to block device. This will fill the entire block device with zeros.
```
nsh> ls -l /dev
/dev:
 brw-rw-rw-       0 ram0
 crw-rw-rw-       0 zero
nsh> dd if=/dev/zero of=/dev/ram0
```
3. Read from a block device, write to a character device. This will read the entire block device and dump the contents in the bit bucket.
```
nsh> ls -l /dev
/dev:
 crw-rw-rw-       0 null
 brw-rw-rw-       0 ram0
nsh> dd if=/dev/ram0 of=/dev/null
```
delroute <target> [<netmask>]

This command removes an entry from the routing table. The entry removed will be the first entry in the routing table that matches the external network characterized by the <target> IP address and the network mask <netmask>

The netmask may also be expressed using IPv4 CIDR or IPv6 slash notation. In that case, the netmask need not be provided.

Example:
```
nsh> delroute 11.0.0.0 255.255.255.0
```
which is equivalent to
```
nsh> delroute 11.0.0.0/24
```

df

Show the state of each mounted volume.

Example:

nsh> mount
/etc type romfs
/tmp type vfat
nsh> df
  Block  Number
  Size   Blocks     Used Available Mounted on
    64        6        6         0 /etc
   512      985        2       983 /tmp
nsh>

dirname <path>

Extract the path string leading up to the full <path> by removing the final directory or file name.
dmesg

This command can be used to dump (and clear) the content of any buffered syslog output messages. This command is only available if CONFIG_RAMLOG_SYSLOG is enabled. In that case, syslog output will be collected in an in-memory, circular buffer. Entering the dmesg command will dump the content of that in-memory, circular buffer to the NSH console output. dmesg has the side effect of clearing the buffered data so that entering dmesg again will show only newly buffered data.
echo [-n] [<string|$name> [<string|$name>...]]

Copy the sequence of strings and expanded environment variables to console out (or to a file if the output is re-directed).

The -n option will suppress the trailing newline character.
env

Show the current name-value pairs in the environment. Example:
```
nsh> env
PATH=/bin

nsh> set foo bar
nsh> env
PATH=/bin
foo=bar

nsh> unset PATH
nsh> env
foo=bar

nsh>
```
Note: NSH variables are not shown by the env command.
exec <hex-address>

Execute the user logic at address <hex-address>. NSH will pause until the execution unless the user logic is executed in background via exec <hex-address> &
exit

Exit NSH. Only useful if you have started some other tasks (perhaps using the exec command) and you would like to have NSH out of the way.
export <name> [<value>]

The export command sets an environment variable, or promotes an NSH variable to an environment variable. As examples:
1. Using export to promote an NSH variable to an environment variable.
```
nsh> env
PATH=/bin

nsh> set foo bar
nsh> env
PATH=/bin

nsh> export foo
nsh> env
PATH=/bin
foo=bar
```
  A group-wide environment variable is created with the same value as the local NSH variable; the local NSH variable is removed.
  
  Note: This behavior differs from the Bash shell. Bash will retain the local Bash variable which will shadow the environment variable of the same name and same value.
2. Using export to set an environment variable
```
nsh> export dog poop
nsh> env
PATH=/bin
foo=bar
dog=poop
```
The export command is not supported by NSH unless both CONFIG_NSH_VARS=y and CONFIG_DISABLE_ENVIRON is not set.
free

Show the current state of the memory allocator. For example,
```
nsh> free
free
             total       used       free    largest
Mem:       4194288    1591552    2602736    2601584
```
Where:
- total - This is the total size of memory allocated for use by malloc in bytes.
- used - This is the total size of memory occupied by chunks handed out by malloc.
- free - This is the total size of memory occupied by free (not in use) chunks.
- largest - Size of the largest free (not in use) chunk.
get [-b|-n] [-f <local-path>] -h <ip-address> <remote-path>

Use TFTP to copy the file at <remote-address> from the host whose IP address is identified by <ip-address>. Other options:
- -f <local-path> The file will be saved relative to the current working directory unless <local-path> is provided.
- -b|-n Selects either binary (octet) or text (netascii) transfer mode. Default: text.
help [-v] [<cmd>]

Presents summary information about NSH commands to console. Options:
- -v Show verbose output will full command usage.
- <cmd> Show full command usage only for this command.
hexdump <file or device>

Dump data in hexadecimal format from a file or character device.
ifconfig [nic_name [<ip-address>|dhcp]] [dr|gw|gateway <dr-address>] [netmask <net-mask>] [dns <dns-address>] [hw <hw-mac>]

Show the current configuration of the network, for example:
```
nsh> ifconfig
eth0    HWaddr 00:18:11:80:10:06
        IPaddr:10.0.0.2 DRaddr:10.0.0.1 Mask:255.255.255.0
```
if networking statistics are enabled (CONFIG_NET_STATISTICS), then this command will also show the detailed state of transfers by protocol.

Note: This commands depends upon having the procfs file system configured into the system. The procfs file system must also have been mounted with a command like:
```
nsh> mount -t procfs /proc
```
ifdown <interface>

Take down the interface identified by the name <interface>.

Example:
```
ifdown eth0
```
ifup <interface>

Bring up down the interface identified by the name <interface>.

Example:
```
ifup eth0
```

insmod <file-path> <module-name>

Install the loadable OS module at <file-path> as module <module-name>

Example:

nsh> ls -l /mnt/romfs
/mnt/romfs:
  dr-xr-xr-x       0 .
  -r-xr-xr-x    9153 chardev
nsh> ls -l /dev
/dev:
  crw-rw-rw-       0 console
  crw-rw-rw-       0 null
  brw-rw-rw-       0 ram0
  crw-rw-rw-       0 ttyS0
nsh> insmod /mnt/romfs/chardev mydriver
nsh> ls -l /dev
/dev:
  crw-rw-rw-       0 chardev
  crw-rw-rw-       0 console
  crw-rw-rw-       0 null
  brw-rw-rw-       0 ram0
  crw-rw-rw-       0 ttyS0
nsh> lsmod
NAME                 INIT   UNINIT      ARG     TEXT     SIZE     DATA     SIZE
mydriver         20404659 20404625        0 20404580      552 204047a8        0

irqinfo

Show the current count of interrupts taken on all attached interrupts.

Example:

nsh> irqinfo
 IRQ HANDLER  ARGUMENT      COUNT     RATE
   3 00001b3d 00000000        156   19.122
  15 0000800d 00000000        817  100.000
  30 00000fd5 20000018         20    2.490

kill -<signal> <pid>

Send the <signal> to the task identified by <pid>.

losetup [-d <dev-path>] | [[-o <offset>] [-r] <ldev-path> <file-path>]

Setup or teardown the loop device:

Teardown the setup for the loop device at <dev-path>:
```
losetup d <dev-path>
```
Setup the loop device at <dev-path> to access the file at <file-path> as a block device:
```
losetup [-o <offset>] [-r] <dev-path> <file-path>
```

Example:

nsh> dd if=/dev/zero of=/tmp/image bs=512 count=512
nsh> ls -l /tmp
/tmp:
  -rw-rw-rw-   262144 IMAGE
nsh> losetup /dev/loop0 /tmp/image
nsh> ls -l /dev
/dev:
  brw-rw-rw-       0 loop0
nsh> mkfatfs /dev/loop0
nsh> mount -t vfat /dev/loop0 /mnt/example
nsh> ls -l /mnt
ls -l /mnt
/mnt:
  drw-rw-rw-       0 example/
nsh> echo "This is a test" >/mnt/example/atest.txt
nsh> ls -l /mnt/example
/mnt/example:
  -rw-rw-rw-      16 ATEST.TXT
nsh> cat /mnt/example/atest.txt
This is a test
nsh>

ln [-s] <target> <link>

The link command will create a new symbolic link at <link> for the existing file or directory, <target>. This implementation is simplied for use with NuttX in these ways:
- Links may be created only within the NuttX top-level, pseudo file system. No file system currently supported by NuttX provides symbolic links.
- For the same reason, only soft links are implemented.
- File privileges are ignored.
- c_time is not updated.
ls [-lRs] <dir-path>

Show the contents of the directory at <dir-path>. Note: <dir-path> must refer to a directory and no other file system object.

Options:
- -R Show the constents of specified directory and all of its sub-directories.
- -s Show the size of the files along with the filenames in the listing.
- -l Show size and mode information along with the filenames in the listing.
lsmod

Show information about the currently installed OS modules. This information includes:
- The module name assigned to the module when it was installed (NAME, string).
- The address of the module initialization function (INIT, hexadecimal).
- The address of the module un-initialization function (UNINIT, hexadecimal).
- An argument that will be passed to the module un-initialization function (ARG, hexadecimal).
- The start of the .text memory region (TEXT, hexadecimal).
- The size of the .text memory region size (SIZE, decimal).
- The start of the .bss/.data memory region (DATA, hexadecimal).
- The size of the .bss/.data memory region size (SIZE, decimal).
Example:
```
nsh> lsmod
NAME                 INIT   UNINIT      ARG     TEXT     SIZE     DATA     SIZE
mydriver         20404659 20404625        0 20404580      552 204047a8        0
```
md5 [-f] <string or filepath>
mb <hex-address>[=<hex-value>][ <hex-byte-count>] mh <hex-address>[=<hex-value>][ <hex-byte-count>] mw <hex-address>[=<hex-value>][ <hex-byte-count>]

Access memory using byte size access (mb), 16-bit accesses (mh), or 32-bit access (mw). In each case,
- <hex-address>. Specifies the address to be accessed. The current value at that address will always be read and displayed.
- <hex-address>=<hex-value>. Read the value, then write <hex-value> to the location.
- <hex-byte-count>. Perform the mb, mh, or mw operation on a total of <hex-byte-count> bytes, increment the <hex-address> appropriately after each access
Example:
```
nsh> mh 0 16
  0 = 0x0c1e
  2 = 0x0100
  4 = 0x0c1e
  6 = 0x0110
  8 = 0x0c1e
  a = 0x0120
  c = 0x0c1e
  e = 0x0130
  10 = 0x0c1e
  12 = 0x0140
  14 = 0x0c1e
nsh>
```
mkdir <path>

Create the directory at <path>. All components of of <path> except the final directory name must exist on a mounted file system; the final directory must not.

Recall that NuttX uses a pseudo file system for its root file system. The mkdir command can only be used to create directories in volumes set up with the mount command; it cannot be used to create directories in the pseudo file system.

Example:
```
nsh> mkdir /mnt/fs/tmp
nsh> ls -l /mnt/fs
/mnt/fs:
  drw-rw-rw-       0 TESTDIR/
  drw-rw-rw-       0 TMP/
nsh>
```
mkfatfs [-F <fatsize>] [-r <rootdirentries>] <block-driver>

Format a fat file system on the block device specified by <block-driver> path. The FAT size may be provided as an option. Without the <fatsize> option, mkfatfs will select either the FAT12 or FAT16 format. For historical reasons, if you want the FAT32 format, it must be explicitly specified on the command line.

The -r option may be specified to select the the number of entries in the root directory. Typical values for small volumes would be 112 or 224; 512 should be used for large volumes, such as hard disks or very large SD cards. The default is 512 entries in all cases.

The reported number of root directory entries used with FAT32 is zero because the FAT32 root directory is a cluster chain.

NSH provides this command to access the mkfatfs() NuttX API. This block device must reside in the NuttX pseudo file system and must have been created by some call to register_blockdriver() (see include/nuttx/fs/fs.h).
mkfifo <path>

Creates a FIFO character device anywhere in the pseudo file system, creating whatever pseudo directories that may be needed to complete the full path. By convention, however, device drivers are place in the standard /dev directory. After it is created, the FIFO device may be used as any other device driver. NSH provides this command to access the mkfifo() NuttX API.

Example:
```
nsh> ls -l /dev
/dev:
  crw-rw-rw-       0 console
  crw-rw-rw-       0 null
  brw-rw-rw-       0 ram0
nsh> mkfifo /dev/fifo
nsh> ls -l /dev
ls -l /dev
/dev:
  crw-rw-rw-       0 console
  crw-rw-rw-       0 fifo
  crw-rw-rw-       0 null
  brw-rw-rw-       0 ram0
nsh>
```
mkrd [-m <minor>] [-s <sector-size>] <nsectors>

Create a ramdisk consisting of <nsectors>, each of size <sector-size> (or 512 bytes if <sector-size> is not specified). The ramdisk will be registered as /dev/ram<minor>. If <minor> is not specified, mkrd will attempt to register the ramdisk as /dev/ram0.

Example:
```
nsh> ls /dev
/dev:
  console
  null
  ttyS0
  ttyS1
nsh> mkrd 1024
nsh> ls /dev
/dev:
  console
  null
  ram0
  ttyS0
  ttyS1
nsh>
```
Once the ramdisk has been created, it may be formatted using the mkfatfs command and mounted using the mount command.

Example:
```
nsh> mkrd 1024
nsh> mkfatfs /dev/ram0
nsh> mount -t vfat /dev/ram0 /tmp
nsh> ls /tmp
/tmp:
nsh>
```
mount [-t <fstype> [-o <options>] <block-device> <dir-path>]

The mount command performs one of two different operations. If no parameters are provided on the command line after the mount command, then the mount command will enumerate all of the current mountpoints on the console.

If the mount parameters are provided on the command after the mount command, then the mount command will mount a file system in the NuttX pseudo-file system. mount performs a three way association, binding:
- File system. The -t <fstype> option identifies the type of file system that has been formatted on the <block-device>. As of this writing, vfat is the only supported value for <fstype>
- Block Device. The <block-device> argument is the full or relative path to a block driver inode in the pseudo file system. By convention, this is a name under the /dev sub-directory. This <block-device> must have been previously formatted with the same file system type as specified by <fstype>
- Mount Point. The mount point is the location in the pseudo file system where the mounted volume will appear. This mount point can only reside in the NuttX pseudo file system. By convention, this mount point is a subdirectory under /mnt. The mount command will create whatever pseudo directories that may be needed to complete the full path but the full path must not already exist.
After the volume has been mounted in the NuttX pseudo file system, it may be access in the same way as other objects in the file system.

Examples:
```
nsh> ls -l /dev
/dev:
  crw-rw-rw-       0 console
  crw-rw-rw-       0 null
  brw-rw-rw-       0 ram0
nsh> ls /mnt
nsh: ls: no such directory: /mnt
nsh> mount -t vfat /dev/ram0 /mnt/fs
nsh> ls -l /mnt/fs/testdir
/mnt/fs/testdir:
  -rw-rw-rw-      15 TESTFILE.TXT
nsh> echo "This is a test" >/mnt/fs/testdir/example.txt
nsh> ls -l /mnt/fs/testdir
/mnt/fs/testdir:
-rw-rw-rw-      15 TESTFILE.TXT
  -rw-rw-rw-      16 EXAMPLE.TXT
nsh> cat /mnt/fs/testdir/example.txt
This is a test
nsh>

nsh> mount
  /etc type romfs
  /tmp type vfat
  /mnt/fs type vfat
```
mv <old-path> <new-path>

Rename the file object at <old-path> to <new-path>. Both paths must reside in the same mounted file system.
nfsmount <server-address> <mount-point> <remote-path>

Mount the remote NFS server directory <remote-path> at <mount-point> on the target machine. <server-address> is the IP address of the remote server.
nslookup <host-name>

Lookup and print the IP address associated with <host-name>
passwd <username> <password>

Set the password for the existing user <username> to <password>
pmconfig [stay|relax] [normal|idle|standby|sleep]

Control power management subsystem.
poweroff [<n>]

Shutdown and power off the system. This command depends on board- specific hardware support to power down the system. The optional, decimal numeric argument <n> may be included to provide power off mode to board-specific power off logic.

Note: Supporting both the poweroff and shutdown commands is redundant.
printf [\xNN] [\n\r\t] [<string|$name> [<string|$name>...]]

Copy the sequence of strings, characters and expanded environment variables to console out (or to a file if the output is re-directed).

No trailing newline character is added. The escape sequences \n, \r or \t can be used to add line feed, carriage return or tab character to output, respectively.

The hexadecimal escape sequence \xNN takes up to two hexadesimal digits to specify the printed character.

ps

Show the currently active threads and tasks. For example:

nsh> ps
PID PRI POLICY   TYPE    NPX STATE    EVENT     SIGMASK  COMMAND
  0   0 FIFO     Kthread --- Ready              00000000 Idle Task
  1 128 RR       Task    --- Running            00000000 init
  2 128 FIFO     Task    --- Waiting  Semaphore 00000000 nsh_telnetmain()
  3 100 RR       pthread --- Waiting  Semaphore 00000000 <pthread>(21)
nsh>

Note: This commands depends upon having the procfs file system configured into the system. The procfs file system must also have been mounted with a command like:

nsh> mount -t procfs /proc

put [-b|-n] [-f <remote-path>] -h <ip-address> <local-path>

Copy the file at to the host whose IP address is identified by . Other options:
- -f <remote-path> The file will be saved with the same name on the host unless unless <local-path> is provided.
- -b|-n Selects either binary (octet) or test (netascii) transfer mode. Default: text.

pwd

Show the current working directory.

nsh> cd /dev
nsh> pwd
/dev
nsh>

Same as echo $PWD

nsh> echo $PWD
/dev
nsh>

readlink <link>

Show target of a soft link.
reboot [<n>]

Reset and reboot the system immediately. This command depends on hardware support to reset the system. The optional, decimal numeric argument <n> may be included to provide reboot mode to board-specific reboot logic.

Note: Supporting both the reboot and shutdown commands is redundant.
rm <file-path>

Remove the specified <file-path> name from the mounted file system. Recall that NuttX uses a pseudo file system for its root file system. The rm command can only be used to remove (unlink) files in volumes set up with the mount command; it cannot be used to remove names from the pseudo file system.

Example:
```
nsh> ls /mnt/fs/testdir
/mnt/fs/testdir:
  TESTFILE.TXT
  EXAMPLE.TXT
nsh> rm /mnt/fs/testdir/example.txt
nsh> ls /mnt/fs/testdir
/mnt/fs/testdir:
  TESTFILE.TXT
nsh>
```
rmdir <dir-path>

Remove the specified <dir-path> directory from the mounted file system. Recall that NuttX uses a pseudo file system for its root file system. The rmdir command can only be used to remove directories from volumes set up with the mount command; it cannot be used to remove directories from the pseudo file system.

Example:
```
nsh> mkdir /mnt/fs/tmp
nsh> ls -l /mnt/fs
/mnt/fs:
  drw-rw-rw-       0 TESTDIR/
  drw-rw-rw-       0 TMP/
nsh> rmdir /mnt/fs/tmp
nsh> ls -l /mnt/fs
ls -l /mnt/fs
/mnt/fs:
  drw-rw-rw-       0 TESTDIR/
nsh>
```

rmmod <module-name>

Remove the loadable OS module with the <module-name>. Note: An OS module can only be removed if it is not busy.

Example:

nsh> lsmod
NAME                 INIT   UNINIT      ARG     TEXT     SIZE     DATA     SIZE
mydriver         20404659 20404625        0 20404580      552 204047a8        0
nsh> rmmod mydriver
nsh> lsmod
NAME                 INIT   UNINIT      ARG     TEXT     SIZE     DATA     SIZE
nsh>

route ipv4|ipv6

Show the contents of routing table for IPv4 or IPv6.

If only IPv4 or IPv6 is enabled, then the argument is optional but, if provided, must match the enabled internet protocol version.
rptun start|stop <dev-path>

Start or stop the OpenAMP RPC tunnel device at <dev-path>.
set [{+|-}{e|x|xe|ex}] [<name> <value>]

Set the variable <name> to the string <value> and or set NSH parser control options.

For example, a variable may be set like this:
```
nsh> echo $foobar

nsh> set foobar foovalue
nsh> echo $foobar
foovalue
nsh>
```
If CONFIG_NSH_VARS is selected, the effect of this set command is to set the local NSH variable. Otherwise, the group-wide environment variable will be set.

If the local NSH variable has already been 'promoted' to an environment variable, then the set command will set the value of the environment variable rather than the local NSH variable.

Note: The Bash shell does not work this way. Bash would set the value of both the local Bash variable and of the environment variable of the same name to the same value.

If CONFIG_NSH_VARS is selected and no arguments are provided, then the set command will list all list all NSH variables.
```
nsh> set
foolbar=foovalue
```
Set the exit on error control and/or print a trace of commands when parsing scripts in NSH. The settinngs are in effect from the point of execution, until they are changed again, or in the case of the init script, the settings are returned to the default settings when it exits. Included child scripts will run with the parents settings and changes made in the child script will effect the parent on return.

Use set -e to enable and set +e to disable (ignore) the exit condition on commands. The default is -e. Errors cause script to exit.

Use set -x to enable and set +x to disable (silence) printing a trace of the script commands as they are ececuted. The default is +x. No printing of a trace of script commands as they are executed.
- Example 1 - no exit on command not found
```
set +e
notacommand
```
- Example 2 - will exit on command not found
```
set -e
notacommand
```
- Example 3 - will exit on command not found, and print a trace of the script commands
```
set -ex
```
- Example 4 - will exit on command not found, and print a trace of the script commands and set foobar to foovalue.
```
set -ex foobar foovalue
nsh> echo $foobar
foovalue
```
shutdown [--reboot]

Shutdown and power off the system or, optionally, reset and reboot the system immediately. This command depends on hardware support to power down or reset the system; one, both, or neither behavior may be supported.

Note: The shutdown command duplicates the behavior of the poweroff and reboot commands.
sleep <sec>

Pause execution (sleep) of <sec> seconds.
source <script-path>

Execute the sequence of NSH commands in the file referred to by <script-path>.
telnetd

The Telnet daemon may be started either programmatically by calling nsh_telnetstart() or it may be started from the NSH command line using this telnetd command.

Normally this command would be suppressed with CONFIG_NSH_DISABLE_TELNETD because the Telnet daemon is automatically started in nsh_main.c. The exception is when CONFIG_NETINIT_NETLOCAL is selected. IN that case, the network is not enabled at initialization but rather must be enabled from the NSH command line or via other applications.

In that case, calling nsh_telnetstart() before the the network is initialized will fail.
time "<command>"

Perform command timing. This command will execute the following <command> string and then show how much time was required to execute the command. Time is shown with a resolution of 100 microseconds which may be beyond the resolution of many configurations. Note that the <command> must be enclosed in quotation marks if it contains spaces or other delimiters.

Example:
```
nsh> time "sleep 2"

2.0100 sec
nsh>
```
The additional 10 milliseconds in this example is due to the way that the sleep command works: It always waits one system clock tick longer than requested and this test setup used a 10 millisecond periodic system timer. Sources of error could include various quantization errors, competing CPU usage, and the additional overhead of the time command execution itself which is included in the total.

The reported time is the elapsed time from starting of the command to completion of the command. This elapsed time may not necessarily be just the processing time for the command. It may included interrupt level processing, for example. In a busy system, command processing could be delayed if pre-empted by other, higher priority threads competing for CPU time. So the reported time includes all CPU processing from the start of the command to its finish possibly including unrelated processing time during that interval.

Notice that:
```
nsh> time "sleep 2 &"
sleep [3:100]

0.0000 sec
nsh>
```
Since the sleep command is executed in background, the sleep command completes almost immediately. As opposed to the following where the time command is run in background with the sleep command:
```
nsh> time "sleep 2" &
time [3:100]
nsh>
2.0100 sec
```
truncate -s <length> <file-path>

Shrink or extend the size of the regular file at <file-path> to the specified <length>.

A <file-path> argument that does not exist is created. The <length> option is NOT optional.

If a <file-path> is larger than the specified size, the extra data is lost. If a <file-path> is shorter, it is extended and the extended part reads as zero bytes.
umount <dir-path>

Un-mount the file system at mount point <dir-path>. The umount command can only be used to un-mount volumes previously mounted using mount command.

Example:
```
nsh> ls /mnt/fs
/mnt/fs:
  TESTDIR/
nsh> umount /mnt/fs
nsh> ls /mnt/fs
/mnt/fs:
nsh: ls: no such directory: /mnt/fs
nsh>
```
unset <name>

Remove the value associated with the variable <name>. This will remove the name-value pair from both the NSH local variables and the group-wide environment variables. For example:
```
nsh> echo $foobar
foovalue
nsh> unset foobar
nsh> echo $foobar

nsh>
```
urldecode [-f] <string or filepath>
urlencode [-f] <string or filepath>
uname [-a | -imnoprsv]

Print certain system information. With no options, the output is the same as -s.
- -a Print all information, in the following order, except omit -p and -i if unknown:
  - -s, -o, Print the operating system name (NuttX)
  - -n Print the network node hostname (only available if CONFIG_NET=y)
  - -r Print the kernel release
  - -v Print the kernel version
  - -m Print the machine hardware name
  - -i Print the machine platform name
  - -p Print "unknown"
useradd <username> <password>

Add a new user with <username> and <password>
userdel <username>

Delete the user with the name <username>
usleep <usec>

Pause execution (sleep) of <usec> microseconds.
wget [-o <local-path>] <url>

Use HTTP to copy the file at <url> to the current directory. Options:
- -o <local-path> The file will be saved relative to the current working directory and with the same name as on the HTTP server unless <local-path> is provided.

xd <hex-address> <byte-count>

Dump bytes of data from address <hex-address>

Example:

nsh> xd 410e0 512
Hex dump:
0000: 00 00 00 00 9c 9d 03 00 00 00 00 01 11 01 10 06 ................
0010: 12 01 11 01 25 08 13 0b 03 08 1b 08 00 00 02 24 ....%..........$
...
01f0: 08 3a 0b 3b 0b 49 13 00 00 04 13 01 01 13 03 08 .:.;.I..........
nsh>

Built-In Commands

In addition to the commands that are part of NSH listed above, there can be additional, external built-in applications that can be added to NSH. These are separately excecuble programs but will appear much like the commands that are a part of NSH. The primary difference from the user's perspective is that help information about the built-in applications is not directly available from NSH. Rather, you will need to execute the application with the -h option to get help about using the built-in applications.

There are several built-in appliations in the apps/ repository. No attempt is made here to enumerate all of them. But a few of the more common built- in applications are listed below.

ping [-c <count>] [-i <interval>] <ip-address> ping6 [-c <count>] [-i <interval>] <ip-address>

Test the network communication with a remote peer. Example:

nsh> 10.0.0.1
PING 10.0.0.1 56 bytes of data
56 bytes from 10.0.0.1: icmp_seq=1 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=2 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=3 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=4 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=5 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=6 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=7 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=8 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=9 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=10 time=0 ms
10 packets transmitted, 10 received, 0% packet loss, time 10190 ms
nsh>

ping6 differs from ping in that it uses IPv6 addressing.

NSH 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 table 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 bottom of this README file.

Command Dependencies on Configuration Settings

Command	Depends on Configuration
[	!`CONFIG_NSH_DISABLESCRIPT`
addroute	`CONFIG_NET` && `CONFIG_NET_ROUTE`
arp	`CONFIG_NET` && `CONFIG_NET_ARP`
base64dec	`CONFIG_NETUTILS_CODECS` && `CONFIG_CODECS_BASE64`
base64enc	`CONFIG_NETUTILS_CODECS` && `CONFIG_CODECS_BASE64`
basename	-
break	!`CONFIG_NSH_DISABLESCRIPT` && !`CONFIG_NSH_DISABLE_LOOPS`
cat	-
cd	!`CONFIG_DISABLE_ENVIRON`
cp	-
dd	-
delroute	`CONFIG_NET` && `CONFIG_NET_ROUTE`
df	!`CONFIG_DISABLE_MOUNTPOINT`
dirname	-
dmesg	`CONFIG_RAMLOG_SYSLOG`
echo	-
env	`CONFIG_FS_PROCFS` && !`CONFIG_DISABLE_ENVIRON` && !`CONFIG_PROCFS_EXCLUDE_ENVIRON`
exec	-
exit	-
export	`CONFIG_NSH_VARS` && !`CONFIG_DISABLE_ENVIRON`
free	-
get	`CONFIG_NET` && `CONFIG_NET_UDP` && MTU >= 558 (see note 1)
help	-
hexdump	-
ifconfig	`CONFIG_NET` && `CONFIG_FS_PROCFS` && !`CONFIG_FS_PROCFS_EXCLUDE_NET`
ifdown	`CONFIG_NET` && `CONFIG_FS_PROCFS` && !`CONFIG_FS_PROCFS_EXCLUDE_NET`
ifup	`CONFIG_NET` && `CONFIG_FS_PROCFS` && !`CONFIG_FS_PROCFS_EXCLUDE_NET`
insmod	`CONFIG_MODULE`
irqinfo	`CONFIG_FS_PROCFS` && `CONFIG_SCHED_IRQMONITOR`
kill	-
losetup	!`CONFIG_DISABLE_MOUNTPOINT` && `CONFIG_DEV_LOOP`
ln	`CONFIG_PSEUDOFS_SOFTLINK`
ls	-
lsmod	`CONFIG_MODULE` && `CONFIG_FS_PROCFS` && !`CONFIG_FS_PROCFS_EXCLUDE_MODULE`
md5	`CONFIG_NETUTILS_CODECS` && `CONFIG_CODECS_HASH_MD5`
mb,mh,mw	-
mkdir	!`CONFIG_DISABLE_MOUNTPOINT`
mkfatfs	!`CONFIG_DISABLE_MOUNTPOINT` && `CONFIG_FSUTILS_MKFATFS`
mkfifo	`CONFIG_PIPES` && `CONFIG_DEV_FIFO_SIZE` > 0
mkrd	!`CONFIG_DISABLE_MOUNTPOINT`
mount	!`CONFIG_DISABLE_MOUNTPOINT`
mv	!`CONFIG_DISABLE_MOUNTPOINT`
nfsmount	!`CONFIG_DISABLE_MOUNTPOINT` && `CONFIG_NET` && `CONFIG_NFS`
nslookup	`CONFIG_LIBC_NETDB` && `CONFIG_NETDB_DNSCLIENT`
password	!`CONFIG_DISABLE_MOUNTPOINT` && `CONFIG_NSH_LOGIN_PASSWD`
pmconfig	`CONFIG_PM` && !`CONFIG_NSH_DISABLE_PMCONFIG`
poweroff	`CONFIG_BOARDCTL_POWEROFF`
printf	-
ps	`CONFIG_FS_PROCFS` && !`CONFIG_FS_PROCFS_EXCLUDE_PROC`
put	`CONFIG_NET` && `CONFIG_NET_UDP` && MTU >= 558 (see note 1,2)
pwd	!`CONFIG_DISABLE_ENVIRON`
readlink	`CONFIG_PSEUDOFS_SOFTLINK`
reboot	`CONFIG_BOARDCTL_RESET`
rm	!`CONFIG_DISABLE_MOUNTPOINT`
rmdir	!`CONFIG_DISABLE_MOUNTPOINT`
rmmod	`CONFIG_MODULE`
route	`CONFIG_FS_PROCFS` && `CONFIG_FS_PROCFS_EXCLUDE_NET` && !`CONFIG_FS_PROCFS_EXCLUDE_ROUTE` && `CONFIG_NET_ROUTE` && !`CONFIG_NSH_DISABLE_ROUTE` && (`CONFIG_NET_IPv4`
rptun	`CONFIG_RPTUN`
set	`CONFIG_NSH_VARS`
shutdown	`CONFIG_BOARDCTL_POWEROFF`
sleep	-
source	`CONFIG_FILE_STREAM` && !`CONFIG_NSH_DISABLESCRIPT`
test	!`CONFIG_NSH_DISABLESCRIPT`
telnetd	`CONFIG_NSH_TELNET` && !`CONFIG_NSH_DISABLE_TELNETD`
time	-
truncate	!`CONFIG_DISABLE_MOUNTPOINT`
umount	!`CONFIG_DISABLE_MOUNTPOINT`
uname	!`CONFIG_NSH_DISABLE_UNAME`
unset	`CONFIG_NSH_VARS`
urldecode	`CONFIG_NETUTILS_CODECS` && `CONFIG_CODECS_URLCODE`
urlencode	`CONFIG_NETUTILS_CODECS` && `CONFIG_CODECS_URLCODE`
useradd	!`CONFIG_DISABLE_MOUNTPOINT` && `CONFIG_NSH_LOGIN_PASSWD`
userdel	!`CONFIG_DISABLE_MOUNTPOINT` && `CONFIG_NSH_LOGIN_PASSWD`
usleep	-
get	`CONFIG_NET` && `CONFIG_NET_TCP`
xd	-

Notes:

Because of hardware padding, the actual MTU required for put and get operations size may be larger.
Special TFTP server start-up options will probably be required to permit creation of file for the correct operation of the put command.

In addition, each NSH command can be individually disabled via one of the following settings. All of these settings make the configuration of NSH potentially complex but also allow it to squeeze into very small memory footprints.

CONFIG_NSH_DISABLE_ADDROUTE,  CONFIG_NSH_DISABLE_BASE64DEC, CONFIG_NSH_DISABLE_BASE64ENC,
CONFIG_NSH_DISABLE_BASENAME,  CONFIG_NSH_DISABLE_CAT,       CONFIG_NSH_DISABLE_CD,
CONFIG_NSH_DISABLE_CP,        CONFIG_NSH_DISABLE_DD,        CONFIG_NSH_DISABLE_DELROUTE,
CONFIG_NSH_DISABLE_DF,        CONFIG_NSH_DISABLE_DIRNAME,   CONFIG_NSH_DISABLE_DMESG,
CONFIG_NSH_DISABLE_ECHO,      CONFIG_NSH_DISABLE_ENV,       CONFIG_NSH_DISABLE_EXEC,
CONFIG_NSH_DISABLE_EXIT,      CONFIG_NSH_DISABLE_EXPORT,    CONFIG_NSH_DISABLE_FREE,
CONFIG_NSH_DISABLE_GET,       CONFIG_NSH_DISABLE_HELP,      CONFIG_NSH_DISABLE_HEXDUMP,
CONFIG_NSH_DISABLE_IFCONFIG,  CONFIG_NSH_DISABLE_IFUPDOWN,  CONFIG_NSH_DISABLE_KILL,
CONFIG_NSH_DISABLE_LOSETUP,   CONFIG_NSH_DISABLE_LN,        CONFIG_NSH_DISABLE_LS,
CONFIG_NSH_DISABLE_MD5,       CONFIG_NSH_DISABLE_MB,        CONFIG_NSH_DISABLE_MKDIR,
CONFIG_NSH_DISABLE_MKFATFS,   CONFIG_NSH_DISABLE_MKFIFO,    CONFIG_NSH_DISABLE_MKRD,
CONFIG_NSH_DISABLE_MH,        CONFIG_NSH_DISABLE_MODCMDS,   CONFIG_NSH_DISABLE_MOUNT,
CONFIG_NSH_DISABLE_MW,        CONFIG_NSH_DISABLE_MV,        CONFIG_NSH_DISABLE_NFSMOUNT,
CONFIG_NSH_DISABLE_NSLOOKUP,  CONFIG_NSH_DISABLE_PASSWD,    CONFIG_NSH_DISABLE_PING6,
CONFIG_NSH_DISABLE_POWEROFF,  CONFIG_NSH_DISABLE_PRINTF,    CONFIG_NSH_DISABLE_PS,
CONFIG_NSH_DISABLE_PUT,       CONFIG_NSH_DISABLE_PWD,       CONFIG_NSH_DISABLE_READLINK,
CONFIG_NSH_DISABLE_REBOOT,    CONFIG_NSH_DISABLE_RM,        CONFIG_NSH_DISABLE_RPTUN,
CONFIG_NSH_DISABLE_RMDIR,     CONFIG_NSH_DISABLE_ROUTE,     CONFIG_NSH_DISABLE_SET,
CONFIG_NSH_DISABLE_SHUTDOWN,  CONFIG_NSH_DISABLE_SLEEP,     CONFIG_NSH_DISABLE_SOURCE,
CONFIG_NSH_DISABLE_TEST,      CONFIG_NSH_DISABLE_TIME,      CONFIG_NSH_DISABLE_TRUNCATE,
CONFIG_NSH_DISABLE_UMOUNT,    CONFIG_NSH_DISABLE_UNSET,     CONFIG_NSH_DISABLE_URLDECODE,
CONFIG_NSH_DISABLE_URLENCODE, CONFIG_NSH_DISABLE_USERADD,   CONFIG_NSH_DISABLE_USERDEL,
CONFIG_NSH_DISABLE_USLEEP,    CONFIG_NSH_DISABLE_WGET,      CONFIG_NSH_DISABLE_XD

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 Application 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.

Application	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>/configs/<config>/defconfig file:

CONFIG_NSH_READLINE – Selects the minimal implementation of readline(). This minimal implementation provides on backspace for command line editing.
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 support 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.md for more information).
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 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

Command	w/o `CONFIG_NSH_VARS`	w/`CONFIG_NSH_VARS`
`set <a> <b>`	Set environment var `a` to `b`.	Set NSH var `a` to `b`.
`set`	Causes an error.	Lists all NSH variables.
`unset <a>`	Unsets environment var `a`.	Unsets both environment var and NSH var `a`.
`export <a> <b>`	Causes an error.	Unsets NSH var `a`. Sets environment var `a` to `b`.
`export <a>`	Causes an error.	Sets environment var `a` to NSH var `b` (or `""`). Unsets local var `a`.
`env`	Lists all environment variables.	Lists all environment variables (only).

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 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, test, and [ commands and the if-then[-else]-fi 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 command prefix and the & 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 startup script at /etc/init.d/rcS. The default startup 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 the 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.
- 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 read-/write-able USB driver. Default: /dev/ttyACM0.
If there are more than one USB devices, then a USB device minor number may also need to be provided:
- CONFIG_NSH_USBDEV_MINOR – The minor device number of the USB device. Default: 0
- CONFIG_NSH_USBKBD – Normally NSH uses the same device for stdin, stdout, and stderr. By default, that device is /dev/console. If this option is selected, then NSH will use a USB HID keyboard for stdin. In this case, the keyboard is connected directly to the target (via a USB host interface) and the data from the keyboard will drive NSH. NSH output (stdout and stderr) will still go to /dev/console.
- CONFIG_NSH_USBKBD_DEVNAME – If NSH_USBKBD is set to y, then NSH_USBKBD_DEVNAME must also be set to select the USB keyboard device used to support the NSH console input. This should be set to the quoted name of a read- able keyboard driver. Default: /dev/kbda.
- CONFIG_NSH_USBDEV_TRACE – If USB tracing is enabled (CONFIG_USBDEV_TRACE), then NSH can be configured to show the buffered USB trace data after each NSH command:
  
  If CONFIG_NSH_USBDEV_TRACE is selected, then USB trace data can be filtered as follows. 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 CONFIG_NSH_CONDEV

If CONFIG_NSH_CONSOLE is set 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 TELENET 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 if your board provides architecture specific initialization via the board-interface function boardctl(). This function will be called early in NSH initialization to allow board logic to do such things as configure MMC/SD slots.

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

CONFIG_NSH_TELNETD_PORT – The telnet daemon will listen on this TCP port number for connections. Default: 23
CONFIG_NSH_TELNETD_DAEMONPRIO – Priority of the Telnet daemon. Default: SCHED_PRIORITY_DEFAULT
CONFIG_NSH_TELNETD_DAEMONSTACKSIZE – Stack size allocated for the Telnet daemon. Default: 2048
CONFIG_NSH_TELNETD_CLIENTPRIO – Priority of the Telnet client. Default: SCHED_PRIORITY_DEFAULT
CONFIG_NSH_TELNETD_CLIENTSTACKSIZE – 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:

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_IOBUFFER_SIZE – Determines the size of the I/O buffer to use for sending/ receiving TELNET commands/responses.
CONFIG_NETINIT_DHCPC – Obtain the IP address via DHCP.
CONFIG_NETINIT_IPADDR – If CONFIG_NETINIT_DHCPC is NOT set, then the static IP address must be provided.
CONFIG_NETINIT_DRIPADDR – Default router IP address.
CONFIG_NETINIT_NETMASK – Network mask.
CONFIG_NETINIT_NOMAC – Set if your ethernet hardware has no built-in MAC address. If set, a bogus MAC will be assigned.

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

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:

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 /.
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 /.
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 rcS file used when CONFIG_NSH_ROMFSETC is selected, it will mount a FAT FS under /tmp. The following selections describe that FAT FS.

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.
CONFIG_NSH_FATNSECTORS – This is the number of sectors to use with the FAT FS. Default is 1024. The amount of memory used by the FAT FS will be CONFIG_NSH_FATSECTSIZE * CONFIG_NSH_FATNSECTORS bytes.
CONFIG_NSH_FATMOUNTPT – This is the location where the FAT FS will be mounted. Default is /tmp.

Common Problems

Problem:

The function 'readline' is undefined.

Usual Cause:

The following is missing from your defconfig file:

CONFIG_SYSTEM_READLINE=y

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Console / NSH Front End

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`nshlib` NuttShell (NSH)