Delete region of lines with sed

freeindy · 09-21-2008, 12:24 PM

Hi,

How can I delete a region of lines after the matching pattern?
Example, I have the folowing lines

#Superfiction
Superman = Man
batman = Man
Cinderella = Woman

I want when the pattern is matched at "Superfiction", I want all the next three lines including the pattern to be removed.

I've tried:
sed '/Suerfiction/1,3d'

But it doesn't work.
Thanks,
Indy

Kenhelm · 09-21-2008, 12:43 PM

Using GNU sed:-

Code:

sed '/Superfiction/,+3d'

pixellany · 09-21-2008, 01:04 PM

Quote:

I've tried:
sed '/Suerfiction/1,3d'

But it doesn't work.

What syntax were you assuming and what happened? I don't think ranges in SED can be stated in terms of offset from current position, eg, this works:

sed '1,/pattern/ <action>'

But this:

sed '/pattern/,3' <action>'
performs <action> starting with the line containing <pattern>, thru the 3rd line from the beginning

Try this:
sed '/Superfiction/,/^$/d' lines

(removes everything from the line containing "Superfiction" to the first empty line.)

pixellany · 09-21-2008, 01:11 PM

Well---it appears I spoke too soon.

My favorite SED reference (http://www.grymoire.com/Unix/Sed.html) does not cover relative line# addressing. Is this unique to GNU SED?

(I know, I should go look in ABS.....

)

freeindy · 09-21-2008, 01:53 PM

nice, thanks.

Indy

Kenhelm · 09-21-2008, 02:37 PM

@pixellany
GNU sed has these extensions, but I don't know if they are unique to it:-
addr1,+N Matches addr1 and the N lines following addr1.
addr1,~N Matches addr1 and the lines following addr1 until the next line whose input line number is a multiple of N.
They are mentioned here:-
http://www.gnu.org/software/sed/manu...l#sed-Programs

theYinYeti · 09-21-2008, 03:45 PM

Or with any sed:
sed -n '/pattern/ {n; n; n; d}; p'

Yves.

jschiwal · 09-21-2008, 04:12 PM

It is good practice to use blank lines to separate each record. Then 'sed '/pattern/,/^$/d' will do it. It also allows easy extraction, and you can easily read the records into awk as well by simply using RS="".

Look at the output of lspci -v.
e.g.:

Code:

/sbin/lspci -v | sed -n '/Wireless/,/^$/p'