topic Re: how to 'grep' !! in Operating System - HP-UX

how to 'grep' !!

Whitehorse_1 — Mon, 20 Aug 2007 00:34:02 GMT

Admins,

Assume below 'testfile' contains (5 lines),

> cat testfile
apple
apple1
apple2
apple3
apple4
apple5

Qn: Is there anyways I can "grep" only the word "apple". Like,

# grep -? "apple" testfile

I need the output only as "apple".

--WH

Re: how to 'grep' !!

Ralph Grothe — Mon, 20 Aug 2007 01:04:45 GMT

Simply use an anchor

e.g.

$ grep 'apple$' testfile

Re: how to 'grep' !!

AwadheshPandey — Mon, 20 Aug 2007 01:15:17 GMT

u should use grep -x apple testfile.
see man grep

Re: how to 'grep' !!

Ralph Grothe — Mon, 20 Aug 2007 01:20:51 GMT

Addendum,
because a string like "apple" might not be the last string of a record in a file one likely more often has some following fields separated by whitespace or some other separator.
In such a case you could use the extended regexp engine of grep and use something similar to this

$ grep -E 'apple[^[:alnum:]]+'

grep -E or egrep can cope with much more intricate filters (see man regexp).
Albeit, the scope of grep is a bit limited and sometimes one needs a sharper tool like Perl which deserved much of its fame from its intrinsic regular expression capabilities.

Re: how to 'grep' !!

Whitehorse_1 — Mon, 20 Aug 2007 02:20:34 GMT

Thxs Ralph and Awad..

Qn2: If my file contains,

>cat testfile
one
two
three
four
five

How can I grep the words "one" "three" and "four" using a single "grep" command, like,

#grep -? -? "one" -? "three" -? "four"

--WH

Re: how to 'grep' !!

Oviwan — Mon, 20 Aug 2007 02:24:05 GMT

Hey

$ cat yourfile | grep -E "one|three|four"

see also man regexp

Regards

Re: how to 'grep' !!

Ivan Krastev — Mon, 20 Aug 2007 02:27:23 GMT

Use :

cat file| grep -e expr1 -e expr2

grep -e "one" -e "three" -e "four"

regards,
ivan

Re: how to 'grep' !!

AwadheshPandey — Mon, 20 Aug 2007 02:30:27 GMT

u can also use a loop for that,
for i in one three four
do
grep $i testfile
done

Re: how to 'grep' !!

ROCK_10 — Mon, 20 Aug 2007 05:37:29 GMT

Hi,

You can just check this command

cat testfile | grep -i apple

"i" makes it case insensitive.

Thanx

Rahul

Re: how to 'grep' !!

Dennis Handly — Mon, 20 Aug 2007 06:22:16 GMT

You can of course use grep -w, which is made for what you want.

Contrary to what Rahul, Oviwan and Ivan used, you don't have to use cat with grep. grep takes a list of files.

Re: how to 'grep' !!

Hein van den Heuvel — Mon, 20 Aug 2007 07:53:46 GMT

As Ralph corrected himself, the anchor idea is of adequate, but gets mighty combersome for general case where one has to allow for whitespace surrounding it, and begin of line and end of line and what about quotes?

The grep -w option tends to work great, if your grep supports it at all.

Personally I mostly use perl to do my greps and more.
Perl as a "\b" escape for "boundary"

Example:

$ cat > x
apple
apple1
apple2
apple3
snapple
an apple a day
quoted 'apple' test
double-quoted "apple" test
$ perl -ne "print if /\bapple\b/" x
apple
an apple a day
quoted 'apple' test
double-quoted "apple" test

Enjoy.
Hein.