How to print the result of a variable in echo in bash?

Question

I have the following bash script, I would like to print now inside the echo, I receive an error and not able to make it. Could you please point me out in the right direction?

    $now = date -u +"%Y-%m-%dT%H:%M:%SZ"
    echo '
    {
        "a": {
            "timestamp": $now,
        },
    }
    '

Add a shebang and then paste your script there: http://www.shellcheck.net/ — Cyrus, Oct 22 '19 at 15:39
See: [Difference between single and double quotes in bash](http://stackoverflow.com/q/6697753/3776858) — Cyrus, Oct 22 '19 at 15:39
could you please post a working solution, I would be glad to accept an answer :) — Radex, Oct 22 '19 at 15:42
Assignment should be without the dollar sign and without spaces around the equal sign. You should use Command Substitution to capture the output of the `date` command. — choroba, Oct 22 '19 at 15:46

score 2 · Answer 1 · answered Oct 22 '19 at 15:49

First of all your syntax of creating variable now is wrong it should be:

now=$(date -u +"%Y-%m-%dT%H:%M:%SZ")

Then instead of using echo you should use cat that supports here-doc like this:

cat<<-EOF
{
     "a": {
         "timestamp": $now,
     },
}
EOF

This way you don't need to worry about handling quotes and escaping double quotes inside double quotes. Remember that your single quotes in echo don't expand shell variables.

score 0 · Answer 2 · answered Oct 22 '19 at 15:59

You need to have " double quotes to expand shell variables.

Consider:

$ i=22
$ echo "i=$i"
i=22
$ echo 'i=$i'
i=$i

Since you have literal double quotes you want in your interpolated string, you need to backslash escape them:

now=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
echo "{
    \"a\": {
         \"timestamp\": $now,
     },
 }"

Prints:

{
   "a": {
        "timestamp": 2019-10-22T15:52:41Z,
    },
}

How to print the result of a variable in echo in bash?

2 Answers2