I am using the following command: x.txt | grep -w 'in' and I am getting answers like: in into ... etc.
I only want the answer: in
How should i modify the command?
1 Answer
First, the command should be
grep -w in x.txt Your current pipe doesn't work, and it is unnecessary to cat the file just to pipe it. grep can read files directly.
Second, the -w does exactly what you want. From the man page:
-w, --word-regexp
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. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore.
grep will return the complete lines where the word occurs though; that is the function of grep; I mention it to check that you don't get confused because of that.
If you just want to return the word, as you say, you can do
grep -ow in x.txt since -o returns only the matching part, but that seems quite unfruitful. What are you really trying to do?
EDIT: An explicit example:
$ cat test word in word within word word word $ grep -w in test word in word "within" is not matched.
EDIT2: Another example:
$ grep '\<in\>' test word in word EDIT3: It was given that the problem was with Swedish characters. I can reproduce this, even with the environment variable LANG set to sv_SE.UTF-8. https://stackoverflow.com/questions/9260293/egrep-accented-characters-not-recognised-as-part-of-a-word suggests using Perl for UTF-8 specific tasks as the easiest solution.
EDIT4: It seems I can use sed to get this working with Swedish characters:
$ cat test word den word avträden word word word $ sed -n '/\bden\b/p' test word den word $ sed -n '/\<den\>/p' test word den word It is a pragmatic solution, but hopefully it works for this task.
- What I meant was that I only want the line where the complete word is present, i.e. a line where "in" is present but not a line where "within" is present.NewBo– NewBo2012-04-08 12:41:41 +00:00Commented Apr 8, 2012 at 12:41
- 2Yes, but that is exactly what
-wdoes. Does it not work? Give an explicit example where it does not work. I did a test case just now, and it works just as you want, from all I can tell.Daniel Andersson– Daniel Andersson2012-04-08 12:44:30 +00:00Commented Apr 8, 2012 at 12:44 - grep -w "den" ./sv_enb.txt gives the result den;it avträden;privies (I am using OSX)NewBo– NewBo2012-04-08 13:30:38 +00:00Commented Apr 8, 2012 at 13:30
- OSX could very well be relevant. Have you looked at the manual for
grepon your system? Is-wdescribed? Otherwise, you can exchange-w infor'\<in\>', as was trying to be described in the now deleted answer. It could also be some strange unicode error on OSX, but try the above first.Daniel Andersson– Daniel Andersson2012-04-08 13:34:28 +00:00Commented Apr 8, 2012 at 13:34 - grep "\<den\>" ./sv_enb.txt gives den;it avträden;privies. When I read the man pages they are the same as other man pages for grep, no special information about the command in OSX (or OpenBSD).NewBo– NewBo2012-04-08 13:36:06 +00:00Commented Apr 8, 2012 at 13:36
sedto work around the problem.