replace all to "hello" except string that is in between double quotes - regex

Question

$ cat file1
"rome" newyork
"rome"
rome
What do I need to fill in the blank?
$ sed ____________________ file1
I want output like
"rome" newyork
"rome"
hello
if my input is like this
$ cat file1
/temp/hello/ram
hello
/hello/temp/ram
if I want to change the hello that does not have slashes what should I do? (change hello to happy)
temp/hello/ram
happy
/hello/temp/ram

Answer 1

sed 's/[^\"]rome[^\"]/hello/g' your_file
tested below:
> cat temp
"rome" newyork
"rome"
rome
> sed 's/[^\"]rome[^\"]/hello/g' temp
"rome" newyork
"rome"
hello
>

Answer 2

Why is rome changed to hello but newyork is not? If I'm reading the question correctly, you're trying to replace everything not in double quotes with hello?
Depending on the exact use cases you want (what happens to the input string ""?), you probably want something like this:
sed 's/\".*\"/hello/'

Answer 3

I dont see a direct way to replace all others except those enclosed inside " "
However, with recursive sed, a brute force method, you can achieve it.
cat file1 | sed "s/\"rome\"/\"italy\"/g" | sed "s/rome/hello/g" | sed "s/\"italy\"/\"rome\"/g"

Answer 4

The second problem can be solved with a simple perl one-liner (assuming only one hello per line):
perl -pe 'next if /\//; s/hello/happy/;'
The first problem requires some internal book keeping to keep track of whether you are inside a string or not. This can also be solved with perl:
#!/usr/bin/perl -w
use strict;
use warnings;
my $state_outside_string = 0;
my $state_inside_string = 1;
my $state = $state_outside_string;
while (my $line = <>) {
my #chars = split(//,$line);
my $not_yet_printed = "";
foreach my $char (#chars) {
if ($char eq '"') {
if ($state == $state_outside_string) {
$state = $state_inside_string;
$not_yet_printed =~ s/rome/hello/;
print $not_yet_printed;
$not_yet_printed = "";
} else {
$state = $state_outside_string;
}
print $char;
next;
}
if ($state == $state_inside_string) {
print $char;
} else {
$not_yet_printed .= $char;
}
}
$not_yet_printed =~ s/rome/hello/;
print $not_yet_printed;
}