Using sed to delete lines – get 00 after each character

With GNU sed and provided POSIXLY_CORRECT is not in the environment (for single-line input):

sed -i ':a;N;$!ba;s/\n/,/g' test.txt

From https://stackoverflow.com/questions/1251999/sed-how-can-i-replace-a-newline-n :

1. create a label via :a
2. append the current and next line to the pattern space via N
3. if we are before the last line, branch to the created label $!ba ($! means not to do it on the last line (as there should be one final newline)).
4. finally the substitution replaces every newline with a comma on the pattern space (which is the whole file).

sed allows us to define ranges of lines and then apply substitutions only within those ranges. We can define a range starting with a line containing Some/Foo/Bar/String and ending with a line containing } and then apply a substitute command to comment out those lines:

$ sed '\|/Some/Foo/Bar/String|,/}/ s/^/#/' file
#foo { '/Some/Foo/Bar/String' :
#    key1 => value1,
#    key2 => value2,
#    key3 => value3,
#    key4 => value4,
#    key5 => value5,
#}

Details

• \|/Some/Foo/Bar/String|, /}/

  This defines the range. It could have been written as /\/Some\/Foo\/Bar\/String/, /}/ but, to avoid backslashes, I used | as the delimiter in place of / for the first regex.

• s/^/#/

  This is applied only to lines in the range and it comments them out.