I'm familiar with using sed to grab lines between two patterns. For example:
$ cat file
A
PATTERN1
B
PATTERN2
C
$ sed -n '/PATTERN1/,/PATTERN2/p' file
PATTERN1
B
PATTERN2
What I'd like to do, however, is generate this output:
PATTERN1
B
PATTERN2
C
I've come across the {n;p} syntax (example), but I can't seem to shoehorn this into the type of pattern matching I'm doing in this example problem.
You can use N (syntax here is based on GNU sed)
$ sed -n '/PATTERN1/,/PATTERN2/{/PATTERN2/N; p}' ip.txt
PATTERN1
B
PATTERN2
C
Using awk
$ awk '/PATTERN1/{f=1} f || (c && c--); /PATTERN2/{f=0; c=1}' ip.txt
PATTERN1
B
PATTERN2
C
which you can generalize using:
awk -v n=2 '/PATTERN1/{f=1} f || (c && c--); /PATTERN2/{f=0; c=n}'
Further Reading:
This might work for you (GNU sed):
sed -n '/PATTERN1/,/PATTERN2/{p;/PATTERN2/{n;p}}' file
Alternative:
sed '/PATTERN1/{:a;n;/PATTERN2/!ba;n;p};d' file