Scripting for text processing: Delete a set of lines only if entire pattern matches

Question

I want to delete a set of lines (globally) only if the entire pattern matches.

Pattern Description:

Line1:^[#]+ .*

Line2:^[[:space:]]*$

Line3:^-[[:space:]]*$

Line4:^[[:space:]]*$

Line5:^[#]+ .*$|^[-]+[[:space:]]*$

Note:

1. Line3 can have space(s) after -
2. Line2 and Line4 may have a space character or should be blank
3. Line5, either matches ^[#]+ .*$ or ^[-]+[[:space:]]*$
4. I don't want to delete the last line of the pattern i.e. Line5 in the pattern description.

Example:

# Body

- Inside Body

# Summary

-

# Bibliography

- Read this book

Expected output:

# Body

- Inside Body

# Bibliography

- Read this book

---

Note: The provided solution works, is it possible to write it more clearly as follows:

e = '(^|\n)[#]+ .*\
    \n[\t ]*\
    \n-[\t ]*\
    \n[\t ]*\
    \n([#]+ .*|[-]+[\t ]*)\n'

Also, how can we do the provided solution for multiple occurrences of the multiline pattern?

Answer 1

A python solution, should work for python2 or 3. reads from stdin, outputs to stdout. About the only thing I did was change the expression for [[:space:]] to [\t ].

#!/usr/bin/python3

import sys
import re
e='(^|\n)[#]+ .*\n[\t ]*\n-[\t ]*\n[\t ]*\n([#]+ .*|[-]+[\t ]*)\n'
print(re.sub(e, '\\1\\2\n', sys.stdin.read()))