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<h1 class="SECT1"><a name="SAFECHARS">6.12. Fixing Bad
Control Files and Metacharacters</a></h1>
<p>Options used:</p>
<ul>
<li>
<p><tt class="LITERAL">safe_chars=</tt><i class=
"EMPHASIS">additional safe characters for control
file</i></p>
</li>
</ul>
<br>
<br>
<p>RFC1179 defines a simple protocol and standard for print
jobs to be interchanged between print spooling systems.
Unfortunately, there were some major mistakes in not
specifying the exact form that text would take when placed in
the control file.</p>
<p>By default, <b class="APPLICATION">LPRng</b> will brutally
convert a non-conforming RFC1179 control file into one that
is acceptable to most, if not all, existing RFC1179
implementations. In order to prevent problems with <b class=
"APPLICATION">LPRng</b> ruthlessly purges all characters but
upper and lower case letters, spaces, tabs, and <tt class=
"LITERAL">-_.@/:()=,+-%</tt> from the control file, replacing
suspicious characters with underscore (<tt class=
"LITERAL">_</tt>). In addition, <b class=
"APPLICATION">LPRng</b> will ruthlessly regenerate control
file entries and data file names so that they are compliant
with all known RFC1179 implementations.</p>
<p>For some installations, the default set of safe characters
may be overly restrictive. For example, <i class=
"EMPHASIS">vintage</i> software may generate files with <tt
class="LITERAL">#</tt> characters in the <tt class=
"LITERAL">J</tt> line of the control file. The replacement of
this character by underscore (<tt class="LITERAL">_</tt>) may
cause other applications which use the control file
information to stop working. The <tt class=
"LITERAL">:safe_chars</tt> option allows the user to specify
an additional set of safe characters in the <tt class=
"FILENAME">lpd.conf</tt> configuration file(s).</p>
<p>For example, <tt class="LITERAL">:safe_chars=#"</tt> would
allow the <tt class="LITERAL">#</tt> and <tt class=
"LITERAL">"</tt> characters to appear in the control
file.</p>
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