Bash: Variable in single quote

Question

First take a look at this question: Bash or GoogleCL: new line in a string parameter

I want to add a variable ${date} into the "summary" now:

google youtube post ~/videos/cat-falls-down-stairs.avi Comedy \
    --tags 'currency of the internet' \
    --summary $'Today is ${date}. Poor whiskers takes a tumble.\nShe'\''s fine, though, don'\''t worry.'

but variable wont expand inside single quote in bash.

Is is possible to do that?

Note: GoogleCL is a command-line program written in python. I am on Ubuntu 10.10 with Python 2.6.

Answer 1

Rather than attempting to expand a variable inside a single quoted string, the typical solution is to concatenate single and double quoted strings. In other words:

'Today is'"${date}"'. Poor' ...

Answer 2

I'll add yet another option to the list: define a variable as newline, then use that inside double-quotes.

nl=$'\n'
...
   --summary "Today is ${date}. Poor whiskers takes a tumble.${nl}She's fine, though, don't worry."