**eval** is another option:

    $ x="'a b'"
    $ printf '%s,%s' $x
    'a,b'
    $ eval printf '%s,%s' $x
    a b

See also:

- https://unix.stackexchange.com/questions/38440/why-does-bash-variable-expansion-retain-quotes
- http://stackoverflow.com/questions/7454526/bash-variable-containing-multiple-args-with-quotes