Converting a list to double quoted comma separated strings

Question

I have a problem I can't seem able to fix by myself, nor by searching the internets.

I have a list, stored in a file, like this:

apple
banana
pineapple

And I would like each string to be in double quote, and comma separated, like this:

"apple","banana","pineapple"

Ideally, the last word of the list shouldn't have a comma after it, but this is not mandatory.

The idea behind this is to be able to create a JSON formatted document populated by a list of item stored in a plain text file.

Thanks a lot in advance.

Answer 1

awk -v RS='' -v OFS='","' 'NF { $1 = $1; print "\"" $0 "\"" }' file

Output:

"apple","banana","pineapple"

Answer 2

I think that Perl also deserves a mention:

perl -lne 'push @a, qq("$_") }{ print join(",", @a)' file

Builds an array @a containing the value on each line, wrapped in double quotes. Then once the file has been processed, prints out a comma separated list of all the elements in @a.

The so-called eskimo greeting }{ is a shorthand used to create an END block, due to the way that the -n and -p switches are implemented.

Output:

"apple","banana","pineapple"

If it's JSON you're looking for, you could use encode_json:

perl -MJSON -lne 'push @a, $_ }{ print encode_json(\@a)' file

This turns the array into a real JSON-encoded list:

["apple","banana","pineapple"]