NuttShell (NSH)

Last Updated: September 5, 2008



Table of Contents

1.0 Overview

1.1 Console/NSH Front End

1.2 Command Overview

1.3 Conditional Command Execution

1.4 Built-In Variables

1.5 Current Working Directory

1.6 Environment Variables
2.0 Commands.

2.1 Evaluate Expression (test)

2.2 Concatenate Files (cat)

2.3 Change Current Working Directory (cd)

2.4 Copy Files (cp)

2.5 Echo Strings and Variables (echo)

2.6 Execute User Code (exec)

2.7 Get File Via TFTP (get)

2.8 Exit NSH (exit)

2.9 Show Usage Command Usage (help)

2.10 Show Network Configuration (ifconfig)

2.11 List Directory Contents (ls)

2.12 Access Memory (mb, mh, and mw)

2.13 Show Memory Manager Status (mem)

2.14 Show Current Tasks and Threads (ps)

2.15 Create a Directory (mkdir)

2.16 Create a FAT Filesystem (mkfatfs)

2.17 Create a FIFO (mkfifo)

2.18 Create a RAMDISK (mkrd)

2.19 Mount a File System (mount)

2.20 Check Network Peer (ping)

2.21 Send File Via TFTP (put)

2.22 Show Current Working Directory (pwd)

2.23 Remove a File (rm)

2.24 Remove a Directory (rmdir)

2.25 Set an Environment Variable (set)

2.26 Execute an NSH Script (sh)

2.27 Wait for Seconds (sleep)

2.28 Unmount a File System (umount)

2.29 Unset an Environment Variable (unset)

2.30 Wait for Microseconds (usleep)

2.31 Hexadecimal Dump (xd)
3.0 Configuration Settings

3.1 Command Dependencies on Configuration Settings

3.2 NSH-Specific Configuration Settings
Index

1.0 Overview

The examples/nsh sub-directory contains the NuttShell (NSH). NSH is a simple shell application for NuttX.

1.1 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:

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

1.2 Command Overview

Simple, Re-directed, and Background Commands. The NuttShell (NSH) is a simple shell application. NSH supports the following commands forms:

Where:

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

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

1.3 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 commnd). The syntax is as follows:

1.4 Built-In Variables

1.5 Current Working Directory

cd and pwd. 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.

1.6 Environment Variables

Environment Variables:

2.0 Commands

2.1 Evaluate Expression (test)

Command Syntax:

Synopsis. 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:

2.2 Concatenate Files (cat)

Command Syntax:

Synopsis. This command copies and concatentates all of the files at <path> to the console (or to another file if the output is redirected).

2.3 Change Current Working Directory (cd)

Command Syntax:

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

Forms:

2.4 Copy Files (cp)

Command Syntax:

Synopsis. Copy of the contents of the file at <source-path< to the location in the filesystem indicated by <path-path>.

2.5 Echo Strings and Variables (echo)

Command Syntax:

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

2.6 Execute User Code (exec)

Command Syntax:

Synopsis. 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> &.

2.7 Get File Via TFTP (get)

Command Syntax:

Synopsis. Copy the file at <remote-address> from the host whose IP address is identified by <ip-address>.

Other options:

2.8 Exit NSH (exit)

Command Syntax:

Synopsis. Exit NSH. Only useful for the serial front end if you have started some other tasks (perhaps using the exec command) and you would like to have NSH out of the way. For the telnet front-end, exit terminates the telenet session.

2.9 Show Usage Command Usage (help)

Command Syntax:

Synopsis. Presents summary information about each command to console.

2.10 Show Network Configuration (ifconfig)

Command Syntax:

Synopsis. Show the current configuration of the network, for example:

if uIP statistics are enabled (CONFIG_NET_STATISTICS), then this command will also show the detailed state of uIP.

2.11 List Directory Contents (ls)

Command Syntax:

Synopsis. Show the contents of the directory at <dir-path>. NOTE: <dir-path> must refer to a directory and no other filesystem object.

Options:

2.12 Access Memory (mb, mh, and mw)

Command Syntax:

Synopsis. Access memory using byte size access (mb), 16-bit accesses (mh), or 32-bit access (mw). In each case,

Example:

2.13 Show Memory Manager Status (mem)

Command Syntax:

Synopsis. Show the current state of the memory allocator. For example,

Where:

2.14 Show Current Tasks and Threads (ps)

Command Syntax:

Synopsis. Show the currently active threads and tasks. For example,

2.15 Create a Directory (mkdir)

Command Syntax:

Synopsis. 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.

Limited to Mounted File Systems. Recall that NuttX uses a pseudo filesystem 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 filesystem.

Example:

2.16 Create a FAT Filesystem (mkfatfs)

Command Syntax:

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

2.17 Create a FIFO (mkfifo)

Command Syntax:

Synopsis. Creates a FIFO character device anywhere in the pseudo file system, creating whatever psuedo directories that may be needed to complete the <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

2.18 Create a RAMDISK (mkrd)

Command Syntax:

Synopsis. 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<n> (if <n> is not specified, mkrd will attempt to register the ramdisk as /dev/ram0.

Example

Once the ramdisk has been created, it may be formatted using the mkfatfs command and mounted using the mount command.

Example

2.19 Mount a File System (mount)

Command Syntax:

Synopsis. The 'm ount' command mounts a file system in the NuttX psuedo filesystem. 'mount' performs a three way associating, binding:

  1. 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>
  2. Block Device. The <block-device> argument is the full or relative path to a block driver inode in the pseudo filesystem. 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>
  3. Mount Point. The mount point, <dir-path>, is the location in the pseudo filesystem where the mounted volume will appear. This mount point can only reside in the NuttX pseudo filesystem. By convention, this mount point is a subdirectory under /mnt. The mount command will create whatever psuedo directories that may be needed to complete the full path but the full path must not already exist.

After the the volume has been mounted in the NuttX pseudo filesystem, it may be access in the same way as other objects in thefile system.

Example

2.20 Check Network Peer (ping)

Command Syntax:

Synopsis. Test the network communication with a remote peer. Example,

2.21 Send File Via TFTP (put)

Command Syntax:

Synopsis. Copy the file at <local-address> to the host whose IP address is identified by <ip-address>.

Other options:

2.22 Show Current Working Directory (pwd)

Command Syntax:

Synopsis. Show the current working directory.

Same as echo $PWD.

2.23 Remove a File (rm)

Command Syntax:

Synopsis. Remove the specified <file-path> name from the mounted file system. Recall that NuttX uses a pseudo filesystem 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 in the pseudo filesystem.

Example:

2.24 Remove a Directory (rmdir)

Command Syntax:

Synopsis. Remove the specified <dir-path> directory from the mounted file system. Recall that NuttX uses a pseudo filesystem 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 filesystem.

Example:

2.25 Set an Environment Variable (set)

Command Syntax:

Synopsis. Set the environment variable <name> to the string <value>. For example,

2.26 Execute an NSH Script (sh)

Command Syntax:

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

2.27 Wait for Seconds (sleep)

Command Syntax:

Synopsis. Pause execution (sleep) for <sec> seconds.

2.28 Unmount a File System (umount)

Command Syntax:

Synopsis. 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:

2.29 Unset an Environment Variable (unset)

Command Syntax:

Synopsis. Remove the value associated with the environment variable <name>. Example:

    nsh> echo $foobar
    foovalue
    nsh> unset foobar
    nsh> echo $foobar
    
    nsh>
    

2.30 Wait for Microseconds (usleep)

Command Syntax:

    usleep <usec>
    

Synopsis. Pause execution (sleep) of <usec> microseconds.

2.31 Hexadecimal dump (xd)

Command Syntax:

    xd <hex-address> <byte-count>
    

Synopsis. Dump <byte-count> 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>
    

3.0 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 document.

3.1 Command Dependencies on Configuration Settings

Table. Command Dependencies on Configuration Settings

Command Depends on Configuration
[ !CONFIG_EXAMPLES_NSH_DISABLESCRIPT
cat CONFIG_NFILE_DESCRIPTORS > 0
cd !CONFIG_DISABLE_ENVIRON && CONFIG_NFILE_DESCRIPTORS > 0
cp CONFIG_NFILE_DESCRIPTORS > 0
echo
exec
exit
get CONFIG_NET && CONFIG_NET_UDP && CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_NET_BUFSIZE >= 5581
help
ifconfig CONFIG_NET
ls CONFIG_NFILE_DESCRIPTORS > 0
mb,mh,mw
mem
mkdir !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0
mkfatfs !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_FS_FAT
mkfifo CONFIG_NFILE_DESCRIPTORS > 0
mkrd !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_FS_FAT
mount !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_FS_FAT
ping CONFIG_NET && CONFIG_NET_ICMP && CONFIG_NET_ICMP_PING && !CONFIG_DISABLE_CLOCK && !CONFIG_DISABLE_SIGNALS
ps
put CONFIG_NET && CONFIG_NET_UDP && CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_NET_BUFSIZE >= 5581,2
pwd !CONFIG_DISABLE_ENVIRON && CONFIG_NFILE_DESCRIPTORS > 0
rm !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0
rmdir !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0
set !CONFIG_DISABLE_ENVIRON
sh CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_NFILE_STREAMS > 0 && !CONFIG_EXAMPLES_NSH_DISABLESCRIPT
sleep !CONFIG_DISABLE_SIGNALS
test !CONFIG_EXAMPLES_NSH_DISABLESCRIPT
umount !CONFIG_DISABLE_MOUNTPOINT && CONFIG_NFILE_DESCRIPTORS > 0 && CONFIG_FS_FAT
unset !CONFIG_DISABLE_ENVIRON
usleep !CONFIG_DISABLE_SIGNALS

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

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

3.2 NSH-Specific Configuration Settings

The behavior of NSH can be modified with the following settings in the configs/<board-name>/defconfig file:

Configuration Description
CONFIG_EXAMPLES_NSH_FILEIOSIZE Size of a static I/O buffer used for file access (ignored if there is no filesystem).
CONFIG_EXAMPLES_NSH_STRERROR strerror(errno) makes more readable output but strerror() is very large and will not be used unless this setting is y
CONFIG_EXAMPLES_NSH_LINELEN The maximum length of one command line and of one output line. Default: 80
CONFIG_EXAMPLES_NSH_STACKSIZE The stack size to use when spawning new threads or tasks. Such new threads are generated when a command is executed in background or as new TELNET connections are established.
CONFIG_EXAMPLES_NSH_NESTDEPTH The maximum number of nested if-then[-else]-fi sequences that are permissable. Default: 3
CONFIG_EXAMPLES_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_EXAMPLES_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_EXAMPLES_NSH_CONSOLE If CONFIG_EXAMPLES_NSH_CONSOLEis set to y, then a serial console front-end is selected.
CONFIG_EXAMPLES_NSH_TELNET If CONFIG_EXAMPLES_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.

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

Configuration Description
CONFIG_EXAMPLES_NSH_IOBUFFER_SIZE Determines the size of the I/O buffer to use for sending/ receiving TELNET commands/reponses
CONFIG_EXAMPLES_NSH_DHCPC Obtain the the IP address via DHCP.
CONFIG_EXAMPLES_NSH_IPADDR If CONFIG_EXAMPLES_NSH_DHCPC is NOT set, then the static IP address must be provided.
CONFIG_EXAMPLES_NSH_DRIPADDR Default router IP address
CONFIG_EXAMPLES_NSH_NETMASK Network mask
CONFIG_EXAMPLES_NSH_NOMAC Set if your ethernet hardware has no built-in MAC address. If set, a bogus MAC will be assigned.

Index

  • Greeting
  • help
  • if-then[-else]-fi
  • ifconfig
  • ls
  • mb
  • mh
  • mw
  • mem
  • mkdir
  • mkfatfs
  • mkfifo
  • mkrd
  • mount
  • nice
  • OLDPWD
  • Overview
  • ping
  • Prompt
  • ps
  • put
  • pwd
  • PWD
  • Re-directed commands
  • rm
  • rmdir
  • set
  • sh
  • Simple commands
  • sleep
  • test
  • umount
  • unset
  • usleep
  • xd