Bug: GNU egrep Breaks with Escaped Curly Brace

GNU egrep (as of version 2.4.2) breaks on \{\} which is used in METASEARCH. My version gives the log entry

"egrep: Invalid content of \{\}"

in Apache's error log.

The GNU grep manpage says the following about this:

      Traditional egrep did not support the { metacharacter, and some egrep implementations support \{ instead,  so  portable  scripts
       should avoid { in egrep patterns and should use [{] to match a literal {.

The following should fix that bug:

--- TWiki.pm.old        Sat Feb  1 18:55:21 2003

+++ TWiki.pm    Thu May  1 22:45:51 2003
@@ -1435,10 +1435,10 @@
     my $searchWeb = "all";

     if( $attrType eq "topicmoved" ) {
-       $searchVal = "%META:TOPICMOVED\{.*from=\\\"$attrWeb\.$attrTopic\\\".*\}%";
+       $searchVal = "%META:TOPICMOVED[{].*from=\\\"$attrWeb\.$attrTopic\\\".*[}]%";
     } elsif ( $attrType eq "parent" ) {
        $searchWeb = $attrWeb;
-       $searchVal = "%META:TOPICPARENT\{.*name=\\\"($attrWeb\\.)?$attrTopic\\\".*\}%";
+       $searchVal = "%META:TOPICPARENT[{].*name=\\\"($attrWeb\\.)?$attrTopic\\\".*[}]%";
     }

     my $text = &TWiki::Search::searchWeb( "1", $searchWeb, $searchVal, "",

And works on my Debian Linux 3.0r1 stable (Woody).

Test case

%METASEARCH{type="parent" web="Codev" topic="GNUEgrepBreaksWithEscapedCurlyBrace" title="Related: "}%

Environment

-- AlanShields - 02 May 2003

Follow up

Fix record

Now fixed in TWikiAlphaRelease - thanks for the patch!

-- RichardDonkin - 02 May 2003

I get a crash when I run TWiki on a DEC Unix system which does not have GNU egrep, but rather a DEC implementation. The error is similar to the one that your patch is intended to fix. But I fixed it by adding more back slash around squiggly brackets in the grep command line.

Here is my patch to Search.pm

290c290,296
<                 $tempVal = `$acmd`;
>
>                #PJ Fix 2003-06-18
>                $acmd =~ s/(\{)/\\\{/ ;
>                $acmd =~ s/(\})/\\}/ ;
>
>
>                $tempVal = `$acmd`;

That works, but I found it by trial and error. Their man page calls for back slashes to protect squiggly braces.

I will try your fix above to see if it works too. But I was curious to ask if you know if these two things are related issues.

-- PaulJohnson