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135 lines
5.3 KiB
HTML
135 lines
5.3 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>system (Debugging with GDB)</title>
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<meta name="description" content="system (Debugging with GDB)">
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<meta name="keywords" content="system (Debugging with GDB)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="List-of-Supported-Calls.html#List-of-Supported-Calls" rel="up" title="List of Supported Calls">
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<link href="Protocol_002dspecific-Representation-of-Datatypes.html#Protocol_002dspecific-Representation-of-Datatypes" rel="next" title="Protocol-specific Representation of Datatypes">
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<link href="isatty.html#isatty" rel="prev" title="isatty">
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<style type="text/css">
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a.summary-letter {text-decoration: none}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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span.roman {font-family: initial; font-weight: normal}
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span.sansserif {font-family: sans-serif; font-weight: normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="system"></a>
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<div class="header">
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<p>
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Previous: <a href="isatty.html#isatty" accesskey="p" rel="prev">isatty</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="system-1"></a>
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<h4 class="unnumberedsubsubsec">system</h4>
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<a name="index-system_002c-file_002di_002fo-system-call"></a>
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<dl compact="compact">
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<dt>Synopsis:</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">int system(const char *command);
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</pre></div>
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</dd>
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<dt>Request:</dt>
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<dd><p>‘<samp>Fsystem,<var>commandptr</var>/<var>len</var></samp>’
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</p>
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</dd>
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<dt>Return value:</dt>
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<dd><p>If <var>len</var> is zero, the return value indicates whether a shell is
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available. A zero return value indicates a shell is not available.
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For non-zero <var>len</var>, the value returned is -1 on error and the
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return status of the command otherwise. Only the exit status of the
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command is returned, which is extracted from the host’s <code>system</code>
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return value by calling <code>WEXITSTATUS(retval)</code>. In case
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<samp>/bin/sh</samp> could not be executed, 127 is returned.
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</p>
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</dd>
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<dt>Errors:</dt>
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<dd>
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<dl compact="compact">
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<dt><code>EINTR</code></dt>
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<dd><p>The call was interrupted by the user.
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</p></dd>
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</dl>
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</dd>
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</dl>
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<p><small>GDB</small> takes over the full task of calling the necessary host calls
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to perform the <code>system</code> call. The return value of <code>system</code> on
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the host is simplified before it’s returned
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to the target. Any termination signal information from the child process
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is discarded, and the return value consists
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entirely of the exit status of the called command.
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</p>
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<p>Due to security concerns, the <code>system</code> call is by default refused
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by <small>GDB</small>. The user has to allow this call explicitly with the
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<code>set remote system-call-allowed 1</code> command.
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</p>
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<dl compact="compact">
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<dt><code>set remote system-call-allowed</code></dt>
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<dd><a name="index-set-remote-system_002dcall_002dallowed"></a>
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<p>Control whether to allow the <code>system</code> calls in the File I/O
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protocol for the remote target. The default is zero (disabled).
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</p>
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</dd>
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<dt><code>show remote system-call-allowed</code></dt>
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<dd><a name="index-show-remote-system_002dcall_002dallowed"></a>
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<p>Show whether the <code>system</code> calls are allowed in the File I/O
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protocol.
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</p></dd>
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</dl>
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</body>
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</html>
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