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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>6.6. pam_env - set/unset environment variables</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><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_echo.html" title="6.5. pam_echo - print text messages"><link rel="next" href="sag-pam_exec.html" title="6.7. pam_exec - call an external command"></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">6.6. pam_env - set/unset environment variables</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="sag-pam_echo.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_exec.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_env"></a>6.6. pam_env - set/unset environment variables</h2></div></div></div><div class="cmdsynopsis"><p><code class="command">pam_env.so</code> [
debug
] [
conffile=<em class="replaceable"><code>conf-file</code></em>
] [
envfile=<em class="replaceable"><code>env-file</code></em>
] [
readenv=<em class="replaceable"><code>0|1</code></em>
] [
user_envfile=<em class="replaceable"><code>env-file</code></em>
] [
user_readenv=<em class="replaceable"><code>0|1</code></em>
]</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env-description"></a>6.6.1. DESCRIPTION</h3></div></div></div><p>
The pam_env PAM module allows the (un)setting of environment
variables. Supported is the use of previously set environment
variables as well as <span class="emphasis"><em>PAM_ITEM</em></span>s such as
<span class="emphasis"><em>PAM_RHOST</em></span>.
</p><p>
By default rules for (un)setting of variables are taken from the
config file <code class="filename">/etc/security/pam_env.conf</code>. An
alternate file can be specified with the <span class="emphasis"><em>conffile</em></span>
option.
</p><p>
Second a file (<code class="filename">/etc/environment</code> by default) with simple
<span class="emphasis"><em>KEY=VAL</em></span> pairs on separate lines will be read.
With the <span class="emphasis"><em>envfile</em></span> option an alternate file can be specified.
And with the <span class="emphasis"><em>readenv</em></span> option this can be completly disabled.
</p><p>
Third it will read a user configuration file
(<code class="filename">$HOME/.pam_environment</code> by default).
The default file file can be changed with the
<span class="emphasis"><em>user_envfile</em></span> option
and it can be turned on and off with the <span class="emphasis"><em>user_readenv</em></span> option.
</p><p>
Since setting of PAM environment variables can have side effects
to other modules, this module should be the last one on the stack.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env.conf-description"></a>6.6.2. DESCRIPTION</h3></div></div></div><p>
The <code class="filename">/etc/security/pam_env.conf</code> file specifies
the environment variables to be set, unset or modified by
<span class="citerefentry"><span class="refentrytitle">pam_env</span>(8)</span>.
When someone logs in, this file is read and the environment
variables are set according.
</p><p>
Each line starts with the variable name, there are then two possible
options for each variable DEFAULT and OVERRIDE. DEFAULT allows and
administrator to set the value of the variable to some default
value, if none is supplied then the empty string is assumed. The
OVERRIDE option tells pam_env that it should enter in its value
(overriding the default value) if there is one to use. OVERRIDE is
not used, "" is assumed and no override will be done.
</p><p>
<em class="replaceable"><code>VARIABLE</code></em>
[<em class="replaceable"><code>DEFAULT=[value]</code></em>]
[<em class="replaceable"><code>OVERRIDE=[value]</code></em>]
</p><p>
(Possibly non-existent) environment variables may be used in values
using the ${string} syntax and (possibly non-existent) PAM_ITEMs as well
as HOME and SHELL may be used in values using the @{string} syntax. Both
the $ and @ characters can be backslash escaped to be used as literal values
values can be delimited with "", escaped " not supported.
Note that many environment variables that you would like to use
may not be set by the time the module is called.
For example, ${HOME} is used below several times, but
many PAM applications don't make it available by the time you need it.
The special variables @{HOME} and @{SHELL} are expanded to the values
for the user from his <span class="emphasis"><em>passwd</em></span> entry.
</p><p>
The "<span class="emphasis"><em>#</em></span>" character at start of line (no space
at front) can be used to mark this line as a comment line.
</p><p>
The <code class="filename">/etc/environment</code> file specifies
the environment variables to be set. The file must consist of simple
<span class="emphasis"><em>NAME=VALUE</em></span> pairs on separate lines.
The <span class="citerefentry"><span class="refentrytitle">pam_env</span>(8)</span>
module will read the file after the <code class="filename">pam_env.conf</code>
file.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env-options"></a>6.6.3. OPTIONS</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">
<code class="option">conffile=<em class="replaceable"><code>/path/to/pam_env.conf</code></em></code>
</span></dt><dd><p>
Indicate an alternative <code class="filename">pam_env.conf</code>
style configuration file to override the default. This can
be useful when different services need different environments.
</p></dd><dt><span class="term">
<code class="option">debug</code>
</span></dt><dd><p>
A lot of debug information is printed with
<span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span>.
</p></dd><dt><span class="term">
<code class="option">envfile=<em class="replaceable"><code>/path/to/environment</code></em></code>
</span></dt><dd><p>
Indicate an alternative <code class="filename">environment</code>
file to override the default. The syntax are simple
<span class="emphasis"><em>KEY=VAL</em></span> pairs on separate lines. The
<span class="emphasis"><em>export</em></span> instruction can be specified for bash
compatibility, but will be ignored.
This can be useful when different services need different environments.
</p></dd><dt><span class="term">
<code class="option">readenv=<em class="replaceable"><code>0|1</code></em></code>
</span></dt><dd><p>
Turns on or off the reading of the file specified by envfile
(0 is off, 1 is on). By default this option is on.
</p></dd><dt><span class="term">
<code class="option">user_envfile=<em class="replaceable"><code>filename</code></em></code>
</span></dt><dd><p>
Indicate an alternative <code class="filename">.pam_environment</code>
file to override the default.The syntax is the same as
for <span class="emphasis"><em>/etc/environment</em></span>.
The filename is relative to the user home directory.
This can be useful when different services need different
environments.
</p></dd><dt><span class="term">
<code class="option">user_readenv=<em class="replaceable"><code>0|1</code></em></code>
</span></dt><dd><p>
Turns on or off the reading of the user specific environment
file. 0 is off, 1 is on. By default this option is off as user
supplied environment variables in the PAM environment could affect
behavior of subsequent modules in the stack without the consent
of the system administrator.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env-types"></a>6.6.4. MODULE TYPES PROVIDED</h3></div></div></div><p>
The <code class="option">auth</code> and <code class="option">session</code> module
types are provided.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env-return_values"></a>6.6.5. RETURN VALUES</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">PAM_ABORT</span></dt><dd><p>
Not all relevant data or options could be gotten.
</p></dd><dt><span class="term">PAM_BUF_ERR</span></dt><dd><p>
Memory buffer error.
</p></dd><dt><span class="term">PAM_IGNORE</span></dt><dd><p>
No pam_env.conf and environment file was found.
</p></dd><dt><span class="term">PAM_SUCCESS</span></dt><dd><p>
Environment variables were set.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env-files"></a>6.6.6. FILES</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="filename">/etc/security/pam_env.conf</code></span></dt><dd><p>Default configuration file</p></dd><dt><span class="term"><code class="filename">/etc/environment</code></span></dt><dd><p>Default environment file</p></dd><dt><span class="term"><code class="filename">$HOME/.pam_environment</code></span></dt><dd><p>User specific environment file</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env.conf-examples"></a>6.6.7. EXAMPLES</h3></div></div></div><p>
These are some example lines which might be specified in
<code class="filename">/etc/security/pam_env.conf</code>.
</p><p>
Set the REMOTEHOST variable for any hosts that are remote, default
to "localhost" rather than not being set at all
</p><pre class="programlisting">
REMOTEHOST DEFAULT=localhost OVERRIDE=@{PAM_RHOST}
</pre><p>
Set the DISPLAY variable if it seems reasonable
</p><pre class="programlisting">
DISPLAY DEFAULT=${REMOTEHOST}:0.0 OVERRIDE=${DISPLAY}
</pre><p>
Now some simple variables
</p><pre class="programlisting">
PAGER DEFAULT=less
MANPAGER DEFAULT=less
LESS DEFAULT="M q e h15 z23 b80"
NNTPSERVER DEFAULT=localhost
PATH DEFAULT=${HOME}/bin:/usr/local/bin:/bin\
:/usr/bin:/usr/local/bin/X11:/usr/bin/X11
XDG_DATA_HOME @{HOME}/share/
</pre><p>
Silly examples of escaped variables, just to show how they work.
</p><pre class="programlisting">
DOLLAR DEFAULT=\$
DOLLARDOLLAR DEFAULT= OVERRIDE=\$${DOLLAR}
DOLLARPLUS DEFAULT=\${REMOTEHOST}${REMOTEHOST}
ATSIGN DEFAULT="" OVERRIDE=\@
</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="sag-pam_env-authors"></a>6.6.8. AUTHOR</h3></div></div></div><p>
pam_env was written by Dave Kinchlea <kinch@kinch.ark.com>.
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