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

This is like a foot-note to the 2 top answers above (awk & sed). I needed to run it on a large number of files, and hence performance was important. I put the 2 answers to a load-test of 10000 times:

sedTester.sh

for i in `seq 10000`;do sed -n '/PAT1/,/PAT2/{/PAT1/!{/PAT2/!p;};}' patternTester >> sedTesterOutput; done

awkTester.sh

 for i in `seq 10000`;do awk '/PAT1/{flag=1; next} /PAT2/{flag=0} flag' patternTester >> awkTesterOutput; done

Here are the results:

zsh sedTester.sh  11.89s user 39.63s system 81% cpu 1:02.96 total
zsh awkTester.sh  38.73s user 60.64s system 79% cpu 2:04.83 total

sed solutions seems to be twice as fast as the awk solution (Mac OS).