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

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

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>

Simple, Re-directed, and Background Commands. The NuttShell (NSH) is a simple shell application. 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 writable object in the filesystem name space (file or character driver). Such objects will be referred to simply as files throughout this document.

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:

[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.

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:

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

$?	The result of the last simple command execution. On backgrounded commands, this variable holds only the result of spawning the background command.

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.

Environment Variables:

PWD	The current working directory
OLDPWD	The previous working directory

Command Syntax:

[ <expression> ]
test <expression>

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:

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

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> &.

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.

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:

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

Command Syntax:

mkfatfs <path>

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).

Command Syntax:

mkfifo <path>

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

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>

Command Syntax:

mkrd [-m <minor>] [-s <sector-size>] <nsectors>

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

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>

Command Syntax:

mount -t <fstype> <block-device> <dir-path>

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

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>

Same as echo $PWD.

nsh> echo $PWD
/dev
nsh>

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:

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>

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:

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
/mnt/fs:
 drw-rw-rw-       0 TESTDIR/
nsh>