How to find patterns across multiple lines using grep?

Question

I want to find files that have \"abc\" AND \"efg\" in that order, and those two strings are on different lines in that file. Eg: a file with content:

blah bl         


        

Answer 1

I used this to extract a fasta sequence from a multi fasta file using the -P option for grep:

grep -Pzo ">tig00000034[^>]+"  file.fasta > desired_sequence.fasta

• P for perl based searches
• z for making a line end in 0 bytes rather than newline char
• o to just capture what matched since grep returns the whole line (which in this case since you did -z is the whole file).

The core of the regexp is the [^>] which translates to "not greater than symbol"