who.html

IEEE 1003.1-2003, Single Unix Specification v3

opposed to multi-byte characters in arguments).</dd>

<dt><i>LC_MESSAGES</i></dt>

<dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard
error.</dd>

<dt><i>LC_TIME</i></dt>

<dd>Determine the locale used for the format and contents of the date and time strings.</dd>

<dt><i>NLSPATH</i></dt>

<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i> <img src="../images/opt-end.gif" alt=
"[Option End]" border="0"></dd>

<dt><i>TZ</i></dt>

<dd>Determine the timezone used when writing date and time information. If <i>TZ</i> is unset or null, an unspecified default
timezone shall be used.</dd>
</dl>
</blockquote>

<h4><a name="tag_04_171_09"></a>ASYNCHRONOUS EVENTS</h4>

<blockquote>
<p>Default.</p>
</blockquote>

<h4><a name="tag_04_171_10"></a>STDOUT</h4>

<blockquote>
<p>The <i>who</i> utility shall write its default format to the standard output in an implementation-defined format, subject only
to the requirement of containing the information described above.</p>

<p><sup>[<a href="javascript:open_code('XSI OF')">XSI OF</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border=
"0"> XSI-conformant systems shall write the default information to the standard output in the following general format:</p>

<pre>
<tt>&lt;</tt><i>name</i><tt>&gt;</tt><b>[</b><tt>&lt;</tt><i>state</i><tt>&gt;</tt><b>]</b><tt>&lt;</tt><i>line</i><tt>&gt;&lt;</tt><i>time</i><tt>&gt;</tt><b>[</b><tt>&lt;</tt><i>activity</i><tt>&gt;</tt><b>][</b><tt>&lt;</tt><i>pid</i><tt>&gt;</tt><b>][</b><tt>&lt;</tt><i>comment</i><tt>&gt;</tt><b>][</b><tt>&lt;</tt><i>exit</i><tt>&gt;</tt><b>]</b> <tt><img
 src="../images/opt-end.gif" border="0">
</tt>
</pre>

<p>The following format shall be used for the <b>-T</b> option:</p>

<pre>
<tt>"%s %c %s %s\n" &lt;</tt><i>name</i><tt>&gt;, &lt;</tt><i>terminal state</i><tt>&gt;, &lt;</tt><i>terminal name</i><tt>&gt;,
    &lt;</tt><i>time of login</i><tt>&gt;
</tt>
</pre>

<p>where &lt;<i>terminal&nbsp;state</i>&gt; is one of the following characters:</p>

<dl compact>
<dt><tt>+</tt></dt>

<dd>The terminal allows write access to other users.</dd>

<dt><tt>-</tt></dt>

<dd>The terminal denies write access to other users.</dd>

<dt><tt>?</tt></dt>

<dd>The terminal write-access state cannot be determined.</dd>
</dl>

<p>In the POSIX locale, the &lt;<i>time&nbsp;of&nbsp;login</i>&gt; shall be equivalent in format to the output of:</p>

<pre>
<tt>date +"%b %e %H:%M"
</tt>
</pre>

<p>If the <b>-u</b> option is used with <b>-T</b>, the idle time shall be added to the end of the previous format in an unspecified
format.</p>
</blockquote>

<h4><a name="tag_04_171_11"></a>STDERR</h4>

<blockquote>
<p>The standard error shall be used only for diagnostic messages.</p>
</blockquote>

<h4><a name="tag_04_171_12"></a>OUTPUT FILES</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_04_171_13"></a>EXTENDED DESCRIPTION</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_04_171_14"></a>EXIT STATUS</h4>

<blockquote>
<p>The following exit values shall be returned:</p>

<dl compact>
<dt>&nbsp;0</dt>

<dd>Successful completion.</dd>

<dt>&gt;0</dt>

<dd>An error occurred.</dd>
</dl>
</blockquote>

<h4><a name="tag_04_171_15"></a>CONSEQUENCES OF ERRORS</h4>

<blockquote>
<p>Default.</p>
</blockquote>

<hr>
<div class="box"><em>The following sections are informative.</em></div>

<h4><a name="tag_04_171_16"></a>APPLICATION USAGE</h4>

<blockquote>
<p>The name <i>init</i> used for the system process is the most commonly used on historical systems, but it may vary.</p>

<p>The &quot;domain of accessibility&quot; referred to is a broad concept that permits interpretation either on a very secure basis or even
to allow a network-wide implementation like the historical <i>rwho</i>.</p>
</blockquote>

<h4><a name="tag_04_171_17"></a>EXAMPLES</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_04_171_18"></a>RATIONALE</h4>

<blockquote>
<p>Due to differences between historical implementations, the base options provided were a compromise to allow users to work with
those functions. The standard developers also considered removing all the options, but felt that these options offered users
valuable functionality. Additional options to match historical systems are available on XSI-conformant systems.</p>

<p>It is recognized that the <i>who</i> command may be of limited usefulness, especially in a multi-level secure environment. The
standard developers considered, however, that having some standard method of determining the &quot;accessibility&quot; of other users would
aid user portability.</p>

<p>No format was specified for the default <i>who</i> output for systems not supporting the XSI Extension. In such a user-oriented
command, designed only for human use, this was not considered to be a deficiency.</p>

<p>The format of the terminal name is unspecified, but the descriptions of <a href="../utilities/ps.html"><i>ps</i></a>, <a href=
"../utilities/talk.html"><i>talk</i></a>, and <a href="../utilities/write.html"><i>write</i></a> require that they use the same
format.</p>

<p>It is acceptable for an implementation to produce no output for an invocation of <i>who</i> <b>mil</b>.</p>
</blockquote>

<h4><a name="tag_04_171_19"></a>FUTURE DIRECTIONS</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_04_171_20"></a>SEE ALSO</h4>

<blockquote>
<p><a href="mesg.html"><i>mesg</i></a></p>
</blockquote>

<h4><a name="tag_04_171_21"></a>CHANGE HISTORY</h4>

<blockquote>
<p>First released in Issue 2.</p>
</blockquote>

<h4><a name="tag_04_171_22"></a>Issue 6</h4>

<blockquote>
<p>This utility is marked as part of the User Portability Utilities option.</p>

<p>The <i>TZ</i> entry is added to the ENVIRONMENT VARIABLES section.</p>
</blockquote>

<div class="box"><em>End of informative text.</em></div>

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