snippet grinder <p>Ever had an alphabetical (or not) list of domain names:</p> <code>de.yahoo.com mail.example.org www.aol.com www.example.org www.freshmeat.net www.hotdoggie.com.au</code> <p>... and wished it was sorted by tld (and recursively down the subdomains)?</p> <code>www.hotdoggie.com.au www.aol.com de.yahoo.com www.freshmeat.net mail.example.org www.example.org</code> <p>From the shell, it's a snap: <code>perl -ple'$_=join".",reverse split/\./'</code> reverse the domain components (<code>mail.example.org</code> becomes <code>org.example.mail</code>). This can then be piped to another filter (<i>e.g.</i> <tt>sort</tt>) and then the same filter can be run again to undo the reversal.</p> <p>It's even easier if the command is wrapped up in an alias. (And yes, I know about "Useless use of cat(1)". I'm using it here to show the symmetry of the munging/demunging).</p> <CODE> cat foo | perl -ple'$_=join".",reverse split/\./' | sort | \ perl -ple'$_=join".",reverse split/\./' # or alias tldmunge='perl -ple'"'"'$_=join".",reverse split/\./'"'" cat foo | tldmunge | sort | tldmunge </CODE>