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grep two lines in a file


 
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# 1  
Old 11-24-2009
grep two lines in a file

Hi Everyone,
I have 1.txt
Code:
1
6-6
3-3
word
y
f
6-6
word
5-5
4
5-5
word

The output should be:
Code:
3-3
word
6-6
word
5-5
word

if i use grep, i can grep word, but if i want to get the line with word, and its previous line, how should i do, awk, sed, perl, Smilie

Thanks
# 2  
Old 11-24-2009
Code:
$grep -B 1 "word"

-B 1 is for 1 line before match.
# 3  
Old 11-24-2009
Quote:
Originally Posted by skmdu
Code:
$grep -B 1 "word"

-B 1 is for 1 line before match.
Thanks, but i tried, the output is: Smilie
Code:
3-3
word
--
6-6
word
--
5-5
word

if i do:
Code:
grep -B 1 "word" 1.txt | grep -v "\-\-"

then i can get the correct output. is there any way other than doing grep -v --. thanks

Last edited by jimmy_y; 11-24-2009 at 03:57 AM..
# 4  
Old 11-24-2009
bash shell
Code:
while read -r line
do
 case "$line" in
    word*) printf "%s\n%s\n" $prev $line;;
 esac
 prev=$line
done < "file"

# 5  
Old 11-24-2009
3-3 ## 1 line previous
word ## Matched line
-- ## delimiter
6-6
word
--
5-5
word
-- delimiter given by the grep command.

Code:
$ grep -B 1 "word" a | grep -v "\-\-"

Try this, it will give you the output as you expected.
# 6  
Old 11-24-2009
Quote:
Originally Posted by skmdu
3-3 ## 1 line previous
word ## Matched line
-- ## delimiter
6-6
word
--
5-5
word
-- delimiter given by the grep command.

Code:
$ grep -B 1 "word" a | grep -v "\-\-"

Try this, it will give you the output as you expected.
if grep -B 1 "word" 1.txt, i cannot do grep -v -B 1 " word" 1.txt, how should i use -v with -B? thanks
# 7  
Old 11-24-2009
grep command writes the delimiter to the file STDOUT. but grep command with its options are applicable for STDIN/Givenfilename.

So for your requirement, my guess is, you can not use -v "\-\-" and -B "word" in a single command..
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