• Remove lines with duplicate letters
• grep on find results

tags | word scape, wordscape

% grep -i "^[slev][slev][slev][slev]s$" /usr/share/dict/american-english 
elves
sells

Remove lines with duplicate letters

 % grep -Ei "^[hikers]{5}$" /usr/share/dict/american-english | grep -Eiv "(.).*\1"
...
shire
shirk
skier

compare this with

 % grep -Ei "^[hikers]{5}$" /usr/share/dict/american-english
...
shire
shirk
shirr
sires
sises
skier
skies

which also shows words where some letters are repeated twice.

Use (character){N} and call grep with -E

 % grep -Ei "^[enrich]i([enrich]){2}e$" /usr/share/dict/american-english
Circe
niche
niece

is equivalent to

 % grep -i "^[enrich]i[enrich][enrich]e$" /usr/share/dict/american-english
Circe
niche
niece

Another example:

 % grep -Ei "^([dunes]){2}u([dunes]){2}d$" /usr/share/dict/american-english
unused

To print lines that contain less than N characters

grep -Ev ".{N}" data.txt

For example: To print lines that contain less then 6 characters

grep -Ev ".{6}" data.txt

You can also do

grep -v "......" data.txt

where the . is repeated N times. This is easier to type for small N.

Sample run:

$ cat data.txt
a
ab
abc
abcd
abcde
abcdef
abcdefg

$ grep -v "......" data.txt
a
ab
abc
abcd
abcde

$ grep -Ev ".{6}" data.txt
a
ab
abc
abcd
abcde