Shell Programming and Scripting

The idea is very simple,

Print from sequence_2 to sequence_3, and when you find a pattern sequence_3 just exit.

So i would very well recommend, as after the sequence_3 your file is not read, sed had been quit, so it is efficient too, is it not ?!

> This terminology in sed is PATTERN addressing.

Thanks a lot, thegeek.
I understand it now d
hehe...
Do you have any idea to solve this thread:
https://www.unix.com/shell-programmin...#post302360533
It seems like more difficult and complicated
Thanks a lot for your advice.

Hi Radoulov

Once again I am baffled by the brevity of your code!

You Explained this one to me a few days ago in another post: -

Code:

awk '/_3$/{exit}/_2$/{f=1}f' file

I just don't get these two at all though, why do they work?

Code:

awk '/_3$/{exit}/_2$/,0' infile

Or:

Code:

awk '/_3$/{exit}/_2$/,_' infile

What is the ,0 and ,_ about?

0 is NULL and _ variable is not set, is NULL.
Literal awk will print from first pattern to the end(NULL) but exit on second pattern.

That's why I like radoulov solutions, you have to ask yourself why

Another road to Rome:

Code:

mawk 'BEGIN {RS="\n>"; printf">"} /_2/' infile

The following is more generic and would also work in case the actual label is not "sequence_2" but the OP means the second record and the ">" at the beginning of a line marks the start of a label of a new record:

Code:

mawk 'BEGIN {RS="\n>"; printf">"} NR==2' infile

or gawk. As danmero pointed out, this code does not work with standard awk nor nawk or posix awk. Those versions only accept a single character for RS.

I see Why the single , before the 0 though, what does that mean in this context?

Code:

awk '/_3$/{exit}/_2$/,0' infile

Code:

local $/=">";
open FH,"<a.txt";
while(<FH>){
  print if /sequence.*2/;
}