grep -i "^(.).*\1$" sowpods.txt > output.txt
I'm using a scrabble words list I downloaded named "sowpods.txt" and I am trying to use grep to find all of the 7 letter words in the file that start and end with the same letter .The line I have now is giving me a backreference error so I tried using online guides but they were insanely confusing. Could someone help me do this? Thanks!
I'm also on a mac and am using the default terminal.
This will work as an extended regular expression. You need grep -E:
grep -E -i "^(.).*\1$"
To match 7-letter words you need to replace * with {5}:
grep -E -i "^(.).{5}\1$"
If you want to use basic regular expression (without option -E), you need a backslash \ before the opening and closing brackets:
grep -i '^\(.\).\{5\}\1$' file
Note that it's good idea to use single quote in your grep regex in order to avoid shell parameter expansion.
