Match 2 consecutive lines using grep or sed - sed

Question

I've just spent a couple of hours trying to detect resets on my system from the console log, where I have:
Boot up message // 1st console output on a boot
Shutdown message // Last console output on a CLEAN shutdown
By using grep for the 2 lines above, on the console output, I have text that contains something like:
Boot up message
Shutdown message
Boot up message
Shutdown message
Boot up message
Boot up message
Shutdown message
Where the reset is detectable by 2 consecutive Boot messages. I have a few thousand cycles to go through, so want to be able to use the '-n' switch with grep to print the cycle numbers, giving something like:
1:Boot up message
2-Shutdown message
3:Boot up message
4-Shutdown message
5:Boot up message
6:Boot up message // reset occurred here
7-Shutdown message
How can I use sed/grep (in Cygwin) to find only the consecutive Boot messages?

Answer 1

You can use this sed:
sed -n 'N;/^\(Boot.*\)\n\1/=' file
(OR)
sed -n 'N;/^\(Boot.*\)\n\1/p' file
This will output a line number on which consecutive messages.
Test:
$ cat file
Boot up message
Shutdown message
Boot up message
Shutdown message
Boot up message
Boot up message
Shutdown message
$ sed -n 'N;/^\(Boot.*\)\n\1/p' file
Boot up message
Boot up message