CODEWITHSUNDEEP
linuxbashsed
FenrisWolf
FenrisWolf

Reputation: 21

Can you use sed to delete match and only certain lines after?

Is it possible to use sed to search for a particular block of code and delete the match and only a particular line after it?

For example, if I have a block like this, and want to delete special marker 1 and only the second line after it:

special marker 1
text 1
text 2
text 3

Can I use sed to search for instances of the block and come out with:

text 1
text 3

I am aware of commands like:

sed -i '/START/,/END/ {/special marker 1/{n;n;N;d;}}' filename;

However, this command only leaves me with:

text 1

So it seems to double the next line operation and deletes. Any way to fix this command or do this another way?

Upvotes: 1

Views: 171

Answers (4)

mop
mop

Reputation: 433

sed -i '/START/,/END/ {/special marker 1/{N;N;D};P;d}' filename

Upvotes: 1

RavinderSingh13
RavinderSingh13

Reputation: 133518

try following awk solutions too once.

Solution 1st:

awk '/special marker 1/{;if(getline var){print var;if(getline var1){next};next}} 1'   Input_file

Solution 2nd:

awk '/special marker 1/{getline;if(NF){print};if(NF){;getline};next} 1'  Input_file

Upvotes: 1

Walter A
Walter A

Reputation: 20002

Tell sed to print to skip the 2 lines:

sed -ni '/special marker 1/{n;p;n;n};p' filename

When you only want two lines output, the command can be replaced by

sed -ni '/special marker 1/{n;p;n;n;p}' filename

Upvotes: 3

anubhava
anubhava

Reputation: 785156

Using awk you can do this:

awk '/special marker 1/{p=NR; next} p && NR==p+2{p=0; next} 1' file
text 1
text 3

Upvotes: 1

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