Using sed in Linux to extract lines from a log file

Question

I have a log file which prints the following lines:

01:15:21.882 DEBUG [SampleProcess] 
Sample Message
01:15:21.882 DEBUG [SampleProcess1] 
Summary Report
Sample Text1: 126
Sample Text2: 2330
Sample Text3: 2331
Sample Text4: 0
01:15:21.883 DEBUG [SampleProcess2] 

I was able to extract the Summary Report by using the below sed command

 sed -n '/Summary Report/,/Sample Text4/p' samplefile.log 

However, I also want to print the timestamp when the Sample Report was generated.

So, currently with

sed -n '/Summary Report/,/Sample Text4/p' samplefile.log

I see the output as

Summary Report
    Sample Text1: 126
    Sample Text2: 2330
    Sample Text3: 2331
    Sample Text4: 0

I want the output as

01:15:21.882 DEBUG [SampleProcess1] 
    Summary Report
    Sample Text1: 126
    Sample Text2: 2330
    Sample Text3: 2331
    Sample Text4: 0

Answer 1

This might work for you (GNU sed):

sed -n '/^..:..:..\./{N;/Summary Report/!D;:a;N;/Sample Text4/!ba;s/\n/&    /gp}' file

Switch off automatic printing. If the current line is a timestamp and the next is not a Summary Report, delete the first line and repeat. Otherwise, gather up the following lines until the Sample Text4, indent all but the first line, print and repeat.