Documentation/NuttShell.html: Document recent changes to NSH.
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Gregory Nutt
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<tr align="center" bgcolor="#e4e4e4">
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<td>
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<h1><big><font color="#3c34ec"><i>NuttShell (NSH)</i></font></big></h1>
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<p>Last Updated: June 22, 2018</p>
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<p>Last Updated: August 11, 2018</p>
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</td>
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</tr>
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</table>
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@ -846,28 +846,44 @@ nsh>
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</p>
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<ul>
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<li>
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<b><code>CONFIG_NSH_CMDPARMS</code></b>.
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If selected, then the output from commands, from file applications, and from NSH built-in commands can be used as arguments to other commands.
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The entity to be executed is identified by enclosing the command line in back quotes.
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<p>
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<b><code>CONFIG_NSH_CMDPARMS</code></b>.
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If selected, then the output from commands, from file applications, and from NSH built-in commands can be used as arguments to other commands.
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The entity to be executed is identified by enclosing the command line in back quotes.
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For example,
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<p>
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<ul><pre>
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</p>
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<ul><pre>
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set FOO `myprogram $BAR`
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</pre></ul>
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<p>
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Will execute the program named <code>myprogram</code> passing it the value of the environment variable <code>BAR</code>.
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The value of the environment variable <code>FOO</code> is then set output of <code>myprogram</code> on <code>stdout</code>.
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<p>
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Will execute the program named <code>myprogram</code> passing it the value of the environment variable <code>BAR</code>.
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The value of the environment variable <code>FOO</code> is then set output of <code>myprogram</code> on <code>stdout</code>.
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</p>
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</li>
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<li>
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<b><code>CONFIG_NSH_ARGCAT</code></b>.
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Support concatenation of strings with environment variables or command output. For example:
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<p>
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<b><code>CONFIG_NSH_ARGCAT</code></b>.
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Support concatenation of strings with environment variables or command output. For example:
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</p>
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<ul><pre>
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set FOO XYZ
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set BAR 123
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set FOOBAR ABC_${FOO}_${BAR}
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</pre></ul>
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would set the environment variable <code>FOO</code> to <code>XYZ</code>, <code>BAR</code> to <code>123</code> and <code>FOOBAR</code> to <code>ABC_XYZ_123</code>.
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If <code>CONFIG_NSH_ARGCAT</code> is not selected, then a slightly smaller FLASH footprint results but then also only simple environment variables like <code>$FOO</code> can be used on the command line.
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<p>
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would set the environment variable <code>FOO</code> to <code>XYZ</code>, <code>BAR</code> to <code>123</code> and <code>FOOBAR</code> to <code>ABC_XYZ_123</code>.
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If <code>CONFIG_NSH_ARGCAT</code> is not selected, then a slightly smaller FLASH footprint results but then also only simple environment variables like <code>$FOO</code> can be used on the command line.
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</p>
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</li>
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<li>
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<p>
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<b><code>CONFIG_NSH_QUOTE</code></b>.
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Enables back-slash quoting of certain characters within the command.
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This option is useful for the case where an NSH script is used to dynamically generate a new NSH script.
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In that case, commands must be treated as simple text strings without interpretation of any special characters.
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Special characters such as <code>$</code>, <code>`</code>, <code>"</code>, and others must be retained intact as part of the test string.
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This option is currently only available is <code>CONFIG_NSH_ARGCAT</code> is also selected.
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</p>
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</li>
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</ul>
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@ -886,7 +902,7 @@ set FOOBAR ABC_${FOO}_${BAR}
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(see the <a href="#cmdsh"><code>sh</code></a> command). The syntax is as follows:
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</p>
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<ul><pre>
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if <cmd>
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if [!] <cmd>
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then
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[sequence of <cmd>]
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else
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@ -910,10 +926,10 @@ fi
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<ul>
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<li>
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<p><b><code>while-do-done</code></b>.
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Execute <code>[sequence of <cmd>]</code> as long as <code><cmd></code> has an exit status of zero.
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Execute <code>[sequence of <cmd>]</code> as long as <code><cmd></code> has an exit status of zero (or non-zero if inverted with <code>!</code>).
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The syntax is as follows:
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<ul><pre>
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while <cmd>
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while [!] <cmd>
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do
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[sequence of <cmd>]
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done
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@ -922,10 +938,10 @@ done
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</li>
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<li>
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<p><b><code>until-do-done</code></b>
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Execute <code>[sequence of <cmd>]</code> as long as <code><cmd></code> has a non-zero exit status.
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Execute <code>[sequence of <cmd>]</code> as long as <code><cmd></code> has a non-zero exit status (or zero if inverted with <code>!</code>).
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The syntax is as follows:
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<ul><pre>
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until <cmd>
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until [!] <cmd>
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do
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[sequence of <cmd>]
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done
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@ -934,6 +950,10 @@ done
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</li>
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</ul>
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<p>
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Note that <code>while</code> is equivalent to <code>until</code> if the command result is inverted.
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</p>
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<p><b>The <a href="#cmdbreak"><code>break</code></a> Command</b>.
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A <a href="#cmdbreak"><code>break</code></a> command is also supported.
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The <code>break</code> command is only meaningful within the body of the a while or until loop, between the <code>do</code> and <code>done</code> tokens.
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@ -3941,6 +3961,16 @@ set FOOBAR ABC_${FOO}_${BAR}
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If <code>CONFIG_NSH_ARGCAT</code> is not selected, then a slightly small FLASH footprint results but then also only simple environment variables like <code>$FOO</code> can be used on the command line.
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</td>
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</tr>
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<tr>
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<td valign="top"><b><code>CONFIG_NSH_QUOTE</code></b></td>
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<td>
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Enables back-slash quoting of certain characters within the command.
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This option is useful for the case where an NSH script is used to dynamically generate a new NSH script.
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In that case, commands must be treated as simple text strings without interpretation of any special characters.
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Special characters such as <code>$</code>, <code>`</code>, <code>"</code>, and others must be retained intact as part of the test string.
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This option is currently only available is <code>CONFIG_NSH_ARGCAT</code> is also selected.
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</td>
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</tr>
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<tr>
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<td valign="top"><b><code>CONFIG_NSH_NESTDEPTH</code></b></td>
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<td>
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@ -5488,6 +5518,7 @@ xxd -i romfs_img >nsh_romfsimg.h
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<li><a href="#custinit"><code>CONFIG_NFILE_DESCRIPTORS</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ARCHINIT</code></a></li>
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<li><a href="#custinit"><code>CONFIG_NSH_ARCHROMFS</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ARCHROMFS</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ARGCAT</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_BUILTIN_APPS</code></a></li>
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<li><a href="#custapps"><code>CONFIG_NSH_BUILTIN_APPS</code></a></li>
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@ -5514,11 +5545,11 @@ xxd -i romfs_img >nsh_romfsimg.h
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_NESTDEPTH</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_NETMASK</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_NOMAC</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_QUOTE</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_READLINE</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ROMFSDEVNO</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ROMFSETC</code></a></li>
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<li><a href="#custinit"><code>CONFIG_NSH_ROMFSETC</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ARCHROMFS</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ROMFSMOUNTPT</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_ROMFSSECTSIZE</code></a></li>
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<li><a href="#nshconfiguration"><code>CONFIG_NSH_STRERROR</code></a></li>
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@ -5593,10 +5624,10 @@ xxd -i romfs_img >nsh_romfsimg.h
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<li><a href="#cmdoverview"><code>nice</code></a></li>
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<li><a href="#nshlibrary">NSH library (<code>nshlib</code>)</a></li>
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<li><a href="#custonshlib">NSH library (<code>nshlib</code>), initialization</a></li>
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<li><a href="#custonshlib"><code>nsh_consolemain()</code></a></li>
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</ul></td>
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<td width="34%" valign="top">
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<ul>
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<li><a href="#custonshlib"><code>nsh_consolemain()</code></a></li>
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<li><a href="#custonshlib"><code>nsh_initialize()</code></a></li>
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<li><a href="#custonshlib"><code>nsh_main()</code></a></li>
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<li><a href="#custinit"><code>nsh_main.c</code></a></li>
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