Can grep show only words that match search pattern?

user_178021 0
Viewed 979556

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, I can 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 this possible using grep? Or using another combination of tools?

words grep
15 Answers

I was unsatisfied with awk's hard to remember syntax but I liked the idea of using one utility to do this.

It seems like ack (or ack-grep if you use Ubuntu) can do this easily:

# ack-grep -ho "\bth.*?\b" *

the
the
the
this
thoroughly

If you omit the -h flag you get:

# ack-grep -o "\bth.*?\b" *

some-other-text-file
1:the

some-text-file
1:the
the

yet-another-text-file
1:this
thoroughly

As a bonus, you can use the --output flag to do this for more complex searches with just about the easiest syntax I've found:

# echo "bug: 1, id: 5, time: 12/27/2010" > test-file
# ack-grep -ho "bug: (\d*), id: (\d*), time: (.*)" --output '$1, $2, $3' test-file

1, 5, 12/27/2010
Beau_603710 
grep --color -o -E "Begin.{0,}?End" file.txt

? - Match as few as possible until the End

Tested on macos terminal

user_16496150

ripgrep

Here are the example using ripgrep:

rg -o "(\w+)?th(\w+)?"

It'll match all words matching th.

user_550750
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