Since my bookmarks seem to disappear, I'm blogging the sites I often use to buy my X10 kit. No connections to any, and no endorsements to found. (Until they pay me...)
http://www.laser.com/
http://www.letsautomate.com/
http://www.simplyautomate.co.uk/
http://www.habitek.co.uk/
Malayalam, with 9 letters. Pathetic, huh! Not the just because it's so short, but also the Unix dictionary doesn't have all the interesting words that do contain longer palindromes.
So, using a quick bit of perl lifted from the web the look for palindromes within a file:
perl -nle 'tr/A-Z/a-z/;$m=length();reverse(substr($_,($m/2)+($m%2))) eq substr($_,0,$m/2) ? print : next' /usr/share/dict/words
The output can then be piped in some code to find the longest line of output. I used the code from the longest word typeable with one hand:
awk '{ printf( "%5d: %s\n", length( $0 ), $0 ) }' | sort -r | head
Giving me:
9: malayalam
7: rotator
7: reviver
7: repaper
7: deified
6: terret
6: semmes
6: renner
6: remmer
6: redder
Now to find a bigger dictionary...