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  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

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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   gt  test-file   ack-grep -ho  bug    d    id    d    time        --output   1   2   3  test-file  1  5  12 27 2010

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Cross distribution safe answer  including windows minGW   grep -h  quot    alpha    th   alpha     quot   filename    tr       n    grep -h  quot    alpha    th   alpha     quot   If you re using older versions of grep  like 2 4 2  which do not include the -o option  then use the above  Else use the simpler to maintain version below  Linux cross distribution safe answer grep -oh  quot    alpha    th   alpha     quot   filename   To summarize  -oh outputs the regular expression matches to the file content  and not its filename   just like how you would expect a regular expression to work in vim etc    What word or regular expression you would be searching for then  is up to you  As long as you remain with POSIX and not perl syntax  refer below  More from the manual for grep -o      Print each match  but only the match  not the entire line  -h      Never print filename headers  i e  filenames  with output lines  -w      The expression is searched for as a word  as if surrounded by               lt      and      gt         The reason why the original answer does not work for everyone The usage of  w varies from platform to platform  as it s an extended  quot perl quot  syntax  As such  those grep installations that are limited to work with POSIX character classes use    alpha    and not its perl equivalent of  w  See the Wikipedia page on regular expression for more Ultimately  the POSIX answer above will be a lot more reliable regardless of platform  being the original  for grep As for support of grep without -o option  the first grep outputs the relevant lines  the tr splits the spaces to new lines  the final grep filters only for the respective lines   PS  I know most platforms by now would have been patched for  w     but there are always those that lag behind  Credit for the  quot -o quot  workaround from  AdamRosenfield answer

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To search all the words with start with  icon-  the following command works perfect  I am using Ack here which is similar to grep but with better options and nice formatting   ack -oh --type html   w icon- w     sort   uniq

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It s more simple than you think  Try this   egrep -wo  th  a-z    filename txt       Case Sensitive   egrep -iwo  th  a-z    filename txt       Case Insensitive    Where    egrep  Grep will work with extended regular expression   w      Matches only word words instead of substring   o      Display only matched pattern instead of whole line   i      If u want to ignore case sensitivity

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You could translate spaces to newlines and then grep  e g    cat     tr       n    grep th

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You could pipe your grep output into Perl like this   grep  th      perl -n -e while    w th w   g   print   1 n

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You can also try pcregrep  There is also a -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

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Try grep -o  grep -oh   w th w       Edit  matching from Phil s comment  From the docs   -h  --no-filename     Suppress the prefixing of file names on output  This is the default     when there is only  one  file   or only standard input  to search  -o  --only-matching     Print  only  the matched  non-empty  parts of a matching line      with each such part on a separate output line

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grep command for only matching and perl  grep -o -P  th      filename

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grep -w   Excerpt from grep man page   -w  Select only those lines containing matches that form whole words  The test is that the matching substring  must  either be at the beginning of the line  or preceded by a non-word constituent character

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Just awk  no need combination of tools     awk   for i 1 i lt  NF i    if  i   th   print  i     file the the the this thoroughly

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ripgrep  Here are the example using ripgrep   rg -o    w   th  w       It ll match all words matching th

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cat  -text-file   grep -Eio  th a-z

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I had a similar problem  looking for grep pattern regex and the  matched pattern found  as output   At the end I used egrep  same regex on grep -e or -G didn t give me the same result of egrep  with the option -o  so  I think that could be something similar to  I m NOT a regex Master     egrep -o  the  this 1  thoroughly 1   filename

[grep] Can grep show only words that match search pattern?

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