How to print lines between two patterns, inclusive or exclusive (in sed, AWK or Perl)?

Question

I have a file like the following and I would like to print the lines between two given patterns PAT1 and PAT2.

Answer 1

Here is another approach

Include both patterns (default)

$ awk '/PAT1/,/PAT2/' file
PAT1
3    - first block
4
PAT2
PAT1
7    - second block
PAT2
PAT1
10    - third block

Mask both patterns

$ awk '/PAT1/,/PAT2/{if(/PAT2|PAT1/) next; print}' file
3    - first block
4
7    - second block
10    - third block

Mask start pattern

$ awk '/PAT1/,/PAT2/{if(/PAT1/) next; print}' file
3    - first block
4
PAT2
7    - second block
PAT2
10    - third block

Mask end pattern

$ awk '/PAT1/,/PAT2/{if(/PAT2/) next; print}' file
PAT1
3    - first block
4
PAT1
7    - second block
PAT1
10    - third block