Can grep show only words that match search pattern?

Question

Is there a way to make grep output "words" from files that match the search expression?

If I want to find all the instances of, say, "th" in a number of files you do;

grep "th" *

but the output will be something like (bold is by me);

some-text-file : the cat sat on the mat
some-other-text-file : the quick brown fox
yet-another-text-file : i hope this explains it thoroughly

What I want it to output, using the same search, is;

the
the
the
this
thoroughly

Is it possible? Or using another/combination of tools?

Thanks,

Neil

Answer 1

Just awk...no need combination of tools

# awk '{for(i=1;i<=NF;i++){if($i~/^th/){print $i}}}' file
the
the
the
this
thoroughly

Answer 2

Try grep -o

grep -oh "\w*th\w*" *

Edit: matching from Phil's comment

Answer 3

You could pipe your grep output into Perl like this:

grep "th" * | perl -n -e'while(/(\w*th\w*)/g) {print "$1\n"}'

Answer 4

You could translate spaces to newlines and then grep, e.g.:

cat * | tr ' ' '\n' | grep th

Answer 5

You can olso try pcregrep. There is also -w option in grep but in some cases it doesn't work as expected: (from wikipedia)

cat fruitlist.txt
apple
apples
pineapple
apple-
apple-fruit
fruit-apple

grep -w apple fruitlist.txt
apple
apple-
apple-fruit
fruit-apple

Answer 6

cat *-text-file | grep -Eio "th[a-z]+"