Login or Register to Ask a Question and Join Our Community


Shell Programming and Scripting

Grep pattern only and surrounding lines

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Grep pattern only and surrounding lines
# 1  
Old 07-25-2016
Grep pattern only and surrounding lines
Hello,

I am trying to grep search a pattern and a line before it.

Code:
cat input
>record1
hello1hello2hellonhello3
>record2
helloohello1hello2hello3

When I use, grep with -o option and either of -A/B/C options, I still can't see lines before or after the pattern. But the exact pattern is being printed fine though. Any pointers are appreciated.

Expected output is

Code:
cat input | grep -o "hello[a-z]hello"
>record1
hellonhello
>record2
helloohello

But current output is

Code:
cat input | grep -o -B 1 "hello[a-z]hello"
hellonhello
helloohello


Thanks in advance.
# 2  
Old 07-25-2016
-o and -B are mutually exclusive, -o tells it to show nothing but the matching text. Remove -o.
This User Gave Thanks to Corona688 For This Post:
jacobs.smith
# 3  
Old 07-25-2016
Thank you @Corona688. I had that doubt in mind.

But I would like to see only the pattern and the line before it. Can you please share any comments?
# 4  
Old 07-25-2016
Code:
sed 's/.*\(hello[a-z]hello\).*/\1/' infile

Last edited by rdrtx1; 07-25-2016 at 02:45 PM..
This User Gave Thanks to rdrtx1 For This Post:
jacobs.smith
# 5  
Old 07-25-2016
grep doesn't do that, you can use awk:
Code:
awk 'match($0,/hello[a-z]hello/) { print L ; print substr($0,RSTART,RLENGTH); } ; { L=$0 }' input

This User Gave Thanks to Corona688 For This Post:
jacobs.smith
# 6  
Old 07-25-2016
Amazing! Thank you!
This User Gave Thanks to jacobs.smith For This Post:
Corona688
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Grep all lines with the pattern .sh

Linux version : Oracle Linux 6.5 Shell : bash In the the below text file (someString.text), I want to grep all lines with .sh in it. ie. Only the lines mysript.sh and anotherscript.sh should be returned. My below attempts failed. I gather that in regular expression world, dot (.) is the... (3 Replies)
Discussion started by: John K
3 Replies

2. UNIX for Dummies Questions & Answers

Grep -v lines starting with pattern 1 and not matching pattern 2

Hi all! Thanks for taking the time to view this! I want to grep out all lines of a file that starts with pattern 1 but also does not match with the second pattern. Example: Drink a soda Eat a banana Eat multiple bananas Drink an apple juice Eat an apple Eat multiple apples I... (8 Replies)
Discussion started by: demmel
8 Replies

3. Shell Programming and Scripting

Grep lines before a pattern having some other pattern

Hi All, I am trying to fetch lines before a pattern, I got to know about -B flag in grep but we have to pass the number to get those lines before some pattern say (X), now what if I want to get line/s with some other pattern say (Y) before X pattern? How to get about it? please help. Input:... (5 Replies)
Discussion started by: dips_ag
5 Replies

4. Shell Programming and Scripting

Grep the word from pattern line and update in subsequent lines till next pattern line reached

Hi, I have got the below requirement. please suggest. I have a file like, Processing Item is: /data/ing/cfg2/abc.txt /data/ing/cfg3/bgc.txt Processing Item is: /data/cmd/for2/ght.txt /data/kernal/config.klgt.txt I want to process the above file to get the output file like, ... (5 Replies)
Discussion started by: rbalaj16
5 Replies

5. Shell Programming and Scripting

Possible to grep string based on surrounding strings?

I was wondering if it was possible to grep a pattern based on the surround text. For example, if i have an input file like this: titleA titleB titlex titleC titleD titlex titleE And I want to grep "title" and save the results only if it is not followed with a "titlex". My output... (14 Replies)
Discussion started by: jl487
14 Replies

6. Shell Programming and Scripting

Print the above and below lines for the grep pattern.

Hi, i would like to get the above and below lines of the grep pattern . For ex : file as below: chk1- aaaa 1-Nov chk2 -aaaa ########## chk1-bbbbbb 1-Nov chk2-bbbbbb ######### my search pattern is date : 1-Nov i need the o/p as below chk1- aaaa 1-Nov (6 Replies)
Discussion started by: expert
6 Replies

7. Shell Programming and Scripting

how to get surrounding lines of my grep search?

hi, if I grep a file, sometimes I want to see as an eg 2 lines above and below my grep results. how can this be done thanks (3 Replies)
Discussion started by: JamesByars
3 Replies

8. UNIX for Dummies Questions & Answers

Grep with 8 lines before and after pattern.

OK. I have a file I'd like to be able to grep, but on top of returning the line where the pattern matches, I'd like to be able to get the previous 8 lines and the following 8 lines. Is there a way to do this? (2 Replies)
Discussion started by: mrwatkin
2 Replies

9. Shell Programming and Scripting

how to get surrounding lines of grep result

hi, if i have a file and i want to search for the word error using grep, i usually want to see the surrounding lines too as they contain info about the error. what would be a nice way to achieve this? thanks (6 Replies)
Discussion started by: JamesByars
6 Replies

10. UNIX for Dummies Questions & Answers

How can you show lines surrounding a search string?

I would like to be able to grep (or some such thing) a search argument and then display the line plus the preceding 3 lines of the file and the following 3 lines of the file. Any ideas? Thanks in advance! :D (3 Replies)
Discussion started by: robster
3 Replies
Login or Register to Ask a Question