uselessuseof

typo.

does your grep have an -f option?

   printf linkedintrouble |sha1sum |sed 's/ .*//' |grep -f - combo_not.txt

cut takes a file as an argument. there's no need to start the line with <

   cut -c4-70 combo_not.txt|...

echo abc > file

1. cat file

2. cat < file

3. echo abc|cat

4. echo abc|cat - file

cat can take input from the left, the right, or both

same goes for cut

printf linkedintrouble |openssl sha1|grep -f - combo_not.txt

symmetric?

head -5 /usr/share/dict/words

same result as with xargs

grep petard /usr/share/dict/words

same result as with xargs

not sure what you are trying to demonstrate here

useless use of xargs?

another useless use of cat

cut -c7-40 combo_not.txt|sort|dups|wc -l

what the heck is dups?

cut -c7-40 combo_not.txt|sort|uniq -d|wc -l

export HISTSIZE=0

obligatory comments

- not portable

- useless use of backticks

printf password|openssl sha1|cut -c6-40|grep -f - hacked.txt