grep lines matching a pattern, and the lines before and after the matching until different pattern

Question

Start_pattern
abc
d End_pattern
Start_pattern
abc
d
ef
ghij 
klm
no End_pattern
Start_pattern
abc
def
hij End_pattern
Start_pattern
abc
dhi
jklm End_pattern

Answer 1

Just for completeness I add the sed solution here :

sed -n '/Start_pattern/{:a;N;/End_Pattern/!ba;/ef/p}'

To understand this, you need to think of labels and branches as goto statements

• If Start_pattern is found execute what is between {...}
• Define a label a with :a
• Add the line to the previous record. (N)
• If End_Pattern is found do not goto label a (!ba)
• After End_Pattern is found, execute the last part which states that if the full record contains ef, print the record.