Finding a match and deleting the line above to it..

Shell Programming and Scripting
1

Hi All,
I have a file with the data:

Sun is Hot
Moon is cool
;
 
-- Mon Sep 10 08:54:10 CDT 2012
-- Mon Sep 11 08:54:10 CDT 2012
-- Mon Sep 12 08:54:10 CDT 2012
revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';

I want to remove the line above the line "revoke connect from SREE;" if the above line starts with only "--" otherwise don't delete. This should continue till all the lines above the revoke line, those start with "--" got deleted. If any space or any other character comes it should stop deleting.

Finally my output should look like:

Sun is Hot
Moon is cool
;
 
revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';

Please help me with this.

Thanks!!

Sreenivas

2

Try

$awk '{if($0 ~ /^--/){A[++a]=$0}else if(a && $0 !~ /revoke connect from SREE/){for(i=1;i<=a;i++){print A[a]};a=0}else{print ;a=0}}' file
Sun is Hot
Moon is cool
;

revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';
3 
awk 'END{if(p)printf "%s",p} /^--/{p=p $0 RS; next} /revoke connect from SREE/{p=x} p{$0=p $0; p=x}1' infile
1 Like
4

Hi Pamu,

Thanks for the reply!!

But with that code any other revoke connect lines also getting deleted (ex: revoke connect from CALU is also getting deleted).

My original file:

Sun is Hot
Moon is cool
;

-- Mon Sep 10 08:54:10 CDT 2012
-- Mon Sep 11 08:54:10 CDT 2012
-- Mon Sep 12 08:54:10 CDT 2012
revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';
 
-- Mon Sep 12 08:54:10 CDT 2011
revoke connect from CALU;
delete from = 'CALU';
grant connect to CALU with 'calendar';

After running the below command:

awk '{if($0 ~ /^--/){A[++a]=$0}else if(a && $0 !~ /revoke connect from SREE/){for(i=1;i<=a;i++){print A[a]};a=0}else{print ;a=0}}' file

Output is as follows:

Sun is Hot
Moon is cool
;

revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';
 
-- Mon Sep 12 08:54:10 CDT 2011
delete from = 'CALU';
grant connect to CALU with 'calendar';

In above ouput

revoke connect from CALU;

line is missing. That shouldn't happen. Please correct the code.

And i cann't redirect this output to a temporary file. These changes should happen to the original file itself.

Please help me in getting these two requirements solved.

Thanks,
Sreenivas

---------- Post updated at 09:21 PM ---------- Previous update was at 06:50 PM ----------

Hi Scrutinizer

Thanks for the reply!!

Your code is not working. Please suggest me the solution based on the above requirement.

Thanks,
Sreenivas

5

What isn't working? I get:

Sun is Hot
Moon is cool
;

revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';
 
-- Mon Sep 12 08:54:10 CDT 2011
revoke connect from CALU;
delete from = 'CALU';
grant connect to CALU with 'calendar';

What is your OS and version?

1 Like
6

Hi
Scrutinizer

Awesome!! Thanks alot!!
Your code is working perfect. Previously i used it wrongly. Now i have corrected my mistake. Its working fine.

But i have a concern about how to make the changes in the original file without redirecting stdout to some temporary new file.

Regards,
Sreenivas

7

Hi, you are welcome. What is wrong with redirecting to a new file? You can rename it to the old file afterwards when satisfied with the result. It is the safest way..

1 Like
8

With Sed..

$ uname -rs
SunOS 5.10
$ sed ':l
> /--/{
> /revoke connect from SREE/{
> D
> }
> N
> /--[^-]*--*/!{
> n
> }
> bl
> }' inputfile
Sun is Hot
Moon is cool
;

revoke connect from SREE;
delete from = 'SREE';
grant connect to SREE with 'fastcar8';

-- Mon Sep 12 08:54:10 CDT 2011
revoke connect from CALU;
delete from = 'CALU';
grant connect to CALU with 'calendar';
$
9

Thats okay..No problem..Thank you all for resolving my issue..