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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>6.7. pam_exec - call an external command</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="Linux-PAM_SAG.html" title="The Linux-PAM System Administrators' Guide"><link rel="up" href="sag-module-reference.html" title="Chapter 6. A reference guide for available modules"><link rel="prev" href="sag-pam_env.html" title="6.6. pam_env - set/unset environment variables"><link rel="next" href="sag-pam_faildelay.html" title="6.8. pam_faildelay - change the delay on failure per-application"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">6.7. pam_exec - call an external command</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="sag-pam_env.html">Prev</a> </td><th width="60%" align="center">Chapter 6. A reference guide for available modules</th><td width="20%" align="right"> <a accesskey="n" href="sag-pam_faildelay.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="sag-pam_exec"></a>6.7. pam_exec - call an external command</h2></div></div></div><div class="cmdsynopsis"><p><code class="command">pam_exec.so</code> [ debug ] [ expose_authtok ] [ seteuid ] [ quiet ] [ stdout ] [ log=<em class="replaceable"><code>file</code></em> ] [ type=<em class="replaceable"><code>type</code></em> ] <em class="replaceable"><code>command</code></em> [ <em class="replaceable"><code>...</code></em> ]</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_exec-description"></a>6.7.1. DESCRIPTION</h3></div></div></div><p> pam_exec is a PAM module that can be used to run an external command. </p><p> The child's environment is set to the current PAM environment list, as returned by <span class="citerefentry"><span class="refentrytitle">pam_getenvlist</span>(3)</span> In addition, the following PAM items are exported as environment variables: <span class="emphasis"><em>PAM_RHOST</em></span>, <span class="emphasis"><em>PAM_RUSER</em></span>, <span class="emphasis"><em>PAM_SERVICE</em></span>, <span class="emphasis"><em>PAM_TTY</em></span>, <span class="emphasis"><em>PAM_USER</em></span> and <span class="emphasis"><em>PAM_TYPE</em></span>, which contains one of the module types: <code class="option">account</code>, <code class="option">auth</code>, <code class="option">password</code>, <code class="option">open_session</code> and <code class="option">close_session</code>. </p><p> Commands called by pam_exec need to be aware of that the user can have controll over the environment. </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_exec-options"></a>6.7.2. OPTIONS</h3></div></div></div><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"> <code class="option">debug</code> </span></dt><dd><p> Print debug information. </p></dd><dt><span class="term"> <code class="option">expose_authtok</code> </span></dt><dd><p> During authentication the calling command can read the password from <span class="citerefentry"><span class="refentrytitle">stdin</span>(3)</span>. Only first <span class="emphasis"><em>PAM_MAX_RESP_SIZE</em></span> bytes of a password are provided to the command. </p></dd><dt><span class="term"> <code class="option">log=<em class="replaceable"><code>file</code></em></code> </span></dt><dd><p> The output of the command is appended to <code class="filename">file</code> </p></dd><dt><span class="term"> <code class="option">type=<em class="replaceable"><code>type</code></em></code> </span></dt><dd><p> Only run the command if the module type matches the given type. </p></dd><dt><span class="term"> <code class="option">stdout</code> </span></dt><dd><p> Per default the output of the executed command is written to <code class="filename">/dev/null</code>. With this option, the stdout output of the executed command is redirected to the calling application. It's in the responsibility of this application what happens with the output. The <code class="option">log</code> option is ignored. </p></dd><dt><span class="term"> <code class="option">quiet</code> </span></dt><dd><p> Per default pam_exec.so will echo the exit status of the external command if it fails. Specifying this option will suppress the message. </p></dd><dt><span class="term"> <code class="option">seteuid</code> </span></dt><dd><p> Per default pam_exec.so will execute the external command with the real user ID of the calling process. Specifying this option means the command is run with the effective user ID. </p></dd></dl></div><p> </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_exec-types"></a>6.7.3. MODULE TYPES PROVIDED</h3></div></div></div><p> All module types (<code class="option">auth</code>, <code class="option">account</code>, <code class="option">password</code> and <code class="option">session</code>) are provided. </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_exec-return_values"></a>6.7.4. RETURN VALUES</h3></div></div></div><p> </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">PAM_SUCCESS</span></dt><dd><p> The external command was run successfully. </p></dd><dt><span class="term">PAM_SERVICE_ERR</span></dt><dd><p> No argument or a wrong number of arguments were given. </p></dd><dt><span class="term">PAM_SYSTEM_ERR</span></dt><dd><p> A system error occurred or the command to execute failed. </p></dd><dt><span class="term">PAM_IGNORE</span></dt><dd><p> <code class="function">pam_setcred</code> was called, which does not execute the command. Or, the value given for the type= parameter did not match the module type. </p></dd></dl></div><p> </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_exec-examples"></a>6.7.5. EXAMPLES</h3></div></div></div><p> Add the following line to <code class="filename">/etc/pam.d/passwd</code> to rebuild the NIS database after each local password change: </p><pre class="programlisting"> password optional pam_exec.so seteuid /usr/bin/make -C /var/yp </pre><p> This will execute the command </p><pre class="programlisting">make -C /var/yp</pre><p> with effective user ID. </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_exec-author"></a>6.7.6. AUTHOR</h3></div></div></div><p> pam_exec was written by Thorsten Kukuk <kukuk@thkukuk.de> and Josh Triplett <josh@joshtriplett.org>. </p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sag-pam_env.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sag-module-reference.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sag-pam_faildelay.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">6.6. pam_env - set/unset environment variables </td><td width="20%" align="center"><a accesskey="h" href="Linux-PAM_SAG.html">Home</a></td><td width="40%" align="right" valign="top"> 6.8. pam_faildelay - change the delay on failure per-application</td></tr></table></div></body></html>