how to remove blank lines from a file range in shell

Question

I have a file like this:

something

import (
    "foo1"
    "foo2"
    "foo3"

    "bar"

    "baz"
 )

something

something

I would like a shell command that as result will change the file to:

something

import (
    "foo1"
    "foo2"
    "foo3"
    "bar"
    "baz"
 )

something

something

Or with other words to remove the empty lines in the range of import ( to the closing ) and to leave the empty lines before and after.

Answer 1

sed is appropriate for this:

sed '/^import/,/^[[:space:]]*)/ { /^[[:space:]]*$/ d; }'

This command instructs sed to delete (d) every empty line (/^[[:space:]]*$/) located inside blocks of lines that start from "import" and end with a closing parenthesis (/^import/,/^[[:space:]]*)/)