Question

I want to be able to utilize a ‘grep’ or ‘pcregrep -M’ like solution that parses a log file that fits the following parameters:

• Each log entry can be multiple lines in length
• First line of log entry has the key that I want to search for
• Each key appears on more then one line

So in the example below I would want to return every line that has KEY1 on it and all the supporting lines below it until the next log message.

Log file:
01 Feb 2010 - 10:39:01.755, DEBUG - KEY1:randomtext
        blah
        blah2 T
        blah3 T
        blah4 F
        blah5 F
        blah6
        blah7
01 Feb 2010 - 10:39:01.757, DEBUG - KEY1:somethngelse
01 Feb 2010 - 10:39:01.758, DEBUG - KEY2:randomtest
this is a test
01 Feb 2010 - 10:39:01.760, DEBUG - KEY1:more logs here
01 Feb 2010 - 10:39:01.762, DEBUG - KEY1:eve more here
this is another multiline log entry
keeps on going
but not as long as before
01 Feb 2010 - 10:39:01.763, DEBUG - KEY2:testing
test test test
end of key2
01 Feb 2010 - 10:39:01.762, DEBUG - KEY1:but key 1 is still going
and going
and going
and going
and going
and going
and going
and going
and going
and going
and going
and going
and going
okay enough
01 Feb 2010 - 10:39:01.762, DEBUG - KEY3:and so on
and on

Desired output of searching for KEY1:
01 Feb 2010 - 10:39:01.755, DEBUG - KEY1:randomtext
        blah
        blah2 T
        blah3 T
        blah4 F
        blah5 F
        blah6
        blah7
01 Feb 2010 - 10:39:01.757, DEBUG - KEY1:somethngelse

01 Feb 2010 - 10:39:01.760, DEBUG - KEY1:more logs here
01 Feb 2010 - 10:39:01.762, DEBUG - KEY1:eve more here
this is another multiline log entry
keeps on going
but not as long as before
01 Feb 2010 - 10:39:01.762, DEBUG - KEY1:but key 1 is still going
and going
and going
and going
and going
and going
and going
and going
and going
and going
and going
and going
and going
okay enough

I was trying to do something like:
pcregrep -M ‘KEY1(.*\n)+’ logfile
but definitely doesn’t work right.

Answer 1

Adding on to ghostdog74’s answer (thank you very much btw, it works great)

Now takes command line input in the form of “./parse file key” and handles loglevels of ERROR as well as DEBUG

#!/bin/bash
awk -vkey="$2" '
$0~/DEBUG|ERROR/ && $0 !~key{f=0}
$0~key{ f=1 }
f{print} ' $1