Regular expression to extract header name from c file

Question

How to extract headers from a c file that contains them like this?

#include 
#include    
#include   
         


        

Answer 1

Try:

awk '{match($0,/[<"].*[>"]/);print substr($0,RSTART+1,RLENGTH-2)}' Input_file

Answer 2

This should work:

sed -nr 's/#include\s+[<"]([^>"]+)[>"].*/\1/p'

Answer 3

grep solution: This is using perl regex and printing anything between "<" or '"' on the lines which start with #include.

grep -oP '^#include.*(<|")\K.*(?=>|")' headers
tema4header9.h
tema4header3.h
stdio.h
longnametest/newheader.h
net/header.h
last-test-Zhy3/DrRuheader.h
last-test-8fF7/a5xyheader.h

If you are ok with awk:

awk '/#include/{gsub(/<|>|"/,"",$2);print $2}' headers
tema4header9.h
tema4header3.h
stdio.h
longnametest/newheader.h
net/header.h
last-test-Zhy3/DrRuheader.h
last-test-8fF7/a5xyheader.h