How to make grep only match if the entire line matches?

Question

I have these:

$ cat a.tmp
ABB.log
ABB.log.122
ABB.log.123

I want to find a exact match of ABB.log.

But when I do:

$ grep -w ABB.log a.tmp
ABB.log
ABB.log.122
ABB.log.123

it shows all of the lines.

Can I get what I want using grep?

John Kugelman · Accepted Answer · 2015-08-09 19:39:39Z

206

grep -Fx ABB.log a.tmp

From the grep man page:

-F, --fixed-strings
Interpret PATTERN as a (list of) fixed strings
-x, --line-regexp
Select only those matches that exactly match the whole line.

edited Aug 9, 2015 at 19:39

answered Jan 17, 2011 at 3:56

John Kugelman

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7 Comments

Johnyy Over a year ago

wasn't able to use -F unfortunately.

Gustavo Straube Over a year ago

I'm using grep inside a bash script and this option is better than use a regular expression as suggested in the accepted answer. Because I have some special character inside the variable I'm searching (like .) and I don't have to escape them when using the command.

ReneGAED Over a year ago

best answer IMO because it allows special characters without escaping

ybenjira Over a year ago

This is better because it also works with variables.

trallnag Over a year ago

Notice that the long options don't work with some grep tools like the one on BusyBox

|

mehmet · Accepted Answer · 2018-12-05 20:52:22Z

118

Simply specify the regexp anchors.

grep '^ABB\.log$' a.tmp

edited Dec 5, 2018 at 20:52

mehmet

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answered Jan 17, 2011 at 3:56

user562374

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3 Comments

user562374 Over a year ago

Both anchors (^ and $) are needed.

green69 Over a year ago

Nice one! And if I'm using the regex for the matching from a file? "grep -f patterns a.tmp" ??

Randoms Over a year ago

@green69 Several years late, but you can use sed to add the anchors before passing the patterns to grep: sed -r "s/^(.*)$/^\1$/" patterns.txt | egrep -f - a.tmp

Taryn · Accepted Answer · 2012-03-13 21:03:15Z

24

Here is what I do, though using anchors is the best way:

grep -w "ABB.log " a.tmp

edited Mar 13, 2012 at 21:03

Taryn

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answered Mar 13, 2012 at 0:36

PranavKN

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2 Comments

user765443 Over a year ago

Like this one.. it will return First line match

Jahid Over a year ago

This requires a space after ABB.log, which is not the general case, i.e it will fail most of the time.

Scrutinizer · Accepted Answer · 2013-03-15 11:32:33Z

3

Most suggestions will fail if there so much as a single leading or trailing space, which would matter if the file is being edited by hand. This would make it less susceptible in that case:

grep '^[[:blank:]]*ABB\.log[[:blank:]]*$' a.tmp

A simple while-read loop in shell would do this implicitly:

while read file
do 
  case $file in
    (ABB.log) printf "%s\n" "$file"
  esac
done < a.tmp

answered Mar 15, 2013 at 11:32

Scrutinizer

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Comments

ghostdog74 · Accepted Answer · 2011-01-17 04:05:09Z

2

similarly with awk

 awk '/^ABB\.log$/' file

answered Jan 17, 2011 at 4:05

ghostdog74

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Comments

Community · Accepted Answer · 2017-05-23 11:54:37Z

1

I intend to add some extra explanation regarding the attempts of OP and other answers as well.

You can use John Kugelmans' solution like this too:

grep -x "ABB\.log" a.tmp

quoting the string and escaping the dot (.) makes it to not need the -F flag any more.

You need to escape the . (dot) (because it matches any character (not only .) if not escaped) or use the -F flag with grep. -F flag makes it a fixed string (not a regex).

If you don't quote the string, you may need double backslash to escape the dot (.):

grep -x ABB\\.log a.tmp

Test:

$ echo "ABBElog"|grep -x  ABB.log
ABBElog #matched !!!
$ echo "ABBElog"|grep -x  "ABB\.log"
#returns empty string, no match

Note:

-x forces to match the whole line.
Answers using a non escaped . without -F flag are wrong.
You can avoid -x switch by wrapping your pattern string with ^ and $. In this case make sure you don't use -F, instead escape the ., because -F will prevent the regex interpretation of ^ and $.

EDIT: (Adding extra explanation in regards of @hakre ):

If you want to match a string starting with -, then you should use -- with grep. Whatever follows -- will be taken as an input (not option).

Example:

echo -f |grep -- "-f"     # where grep "-f" will show error
echo -f |grep -F -- "-f"  # whre grep -F "-f" will show error
grep "pat" -- "-file"     # grep "pat" "-file" won't work. -file is the filename

edited May 23, 2017 at 11:54

CommunityBot

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answered Jul 12, 2015 at 14:28

Jahid

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20 Comments

hakre Over a year ago

Did you actually experience that -F was missing in your case? If so, can you please say which case that was?

Jahid Over a year ago

@hakre Did you read my answer completely? I explained (pretty clearly) why -F won't be needed if the . is escaped properly.

hakre Over a year ago

Sure. Sure, I'm just asking: Was -F available when you wrote this? If not, which system were you using? I couldn't find that information in your answer so far, which even now is the case when I re-read it again. So really sure, I read your answer completely at least twice. ;)

Jahid Over a year ago

@hakre Of course -F was available. ( I did say: "or use -F flag with grep")

hakre Over a year ago

Thanks for the insight. Just one littel question remains: If -F is the answer, why bother about escaping? What's your opinion about that?

|

Frédéric Bogaerts · Accepted Answer · 2015-12-14 11:39:11Z

1

This worked well for me when trying to do something similar:

grep -F ABB.log a.tmp

answered Dec 14, 2015 at 11:39

Frédéric Bogaerts

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Comments

user2173461 · Accepted Answer · 2013-03-15 10:10:22Z

-1

    $ cat venky
    ABB.log
    ABB.log.122
    ABB.log.123

    $ cat venky | grep "ABB.log" | grep -v "ABB.log\."
    ABB.log
    $

    $ cat venky | grep "ABB.log.122" | grep -v "ABB.log.122\."
    ABB.log.122
    $

answered Mar 15, 2013 at 10:10

user2173461

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1 Comment

Scrutinizer Over a year ago

This will also match files that end with ABB.log and the dots should be escaped.

user3114790 · Accepted Answer · 2014-07-14 07:33:07Z

-2

This is with HPUX, if the content of the files has space between words, use this:

egrep "[[:space:]]ABC\.log[[:space:]]" a.tmp

answered Jul 14, 2014 at 7:33

user3114790

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1 Comment

Keith Thompson Over a year ago

The OP wanted to match the whole line, not a space-delimited word within the line.

Schlueter · Accepted Answer · 2018-01-02 01:19:02Z

-2

Works for me:

grep "\bsearch_word\b" text_file > output.txt

\b indicates/sets boundaries.

Seems to work pretty fast

edited Jan 2, 2018 at 1:19

Schlueter

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answered May 11, 2016 at 18:53

Surya Chhetri

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1 Comment

Rohan Singh Over a year ago

This also matches any line that contains search_word separated by word boundaries. For example, it would match the line, "foo search_word bar".

Bartosz · Accepted Answer · 2013-04-04 08:51:32Z

-3

I'd prefer:

str="ABB.log"; grep -E "^${str}$" a.tmp

cheers

answered Apr 4, 2013 at 8:51

Bartosz

1

1 Comment

Keith Thompson Over a year ago

That will match ABBxlog

Schlueter · Accepted Answer · 2017-12-24 03:43:49Z

-4

I needed this feature, but also wanted to make sure I did not return lines with a prefix before the ABB.log:

ABB.log
ABB.log.122
ABB.log.123
123ABB.log

grep "\WABB.log$" -w a.tmp

edited Dec 24, 2017 at 3:43

Schlueter

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answered Sep 11, 2012 at 17:33

Jonathan

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1 Comment

Schlueter Over a year ago

This will only match if the leading \W is satisfied, which is any non whitespace character, so xABBxlog.

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