Sample sed script

get_authors.sed

#n <- run sed in -n mode

# This sed script operates on a list of books in the format:

# Title
# Author
# Rating (1 to 5 asterisks)
# --- (separator)

# Is returns every author who has written a book with 'the'
# in the title and a 4 or 5 star rating.

# This is meant to illustrate the use of the hold and
# pattern space. If you really need something like this, use
# multiple commands or something like awk or perl.

# Append three lines to pattern space.
N ; N ; N

# Check for 'the' in title and 4+ star rating.
/.*the.*\n(.*)\n\*{4,5}\n---/I {
    # Replace pattern space with 
    # capture group (author name.)
    s//\1/
    # Append pattern space to hold space.
    H
}

# On last line.
$ {
    # Swap pattern and hold space.
    x
    # Remove starting newline 
    # (it's there by default on hold space.)
    s/^\n//
    # Replace newlines with commas.
    s/\n/, /g
    # Print pattern space.
    p
}